0001140361-24-030662 | S-1 | XBRL Viewer

FAIR VALUE MEASUREMENTS

NOTE 17 – FAIR VALUE MEASUREMENTS

The fair value of the Company’s financial assets and liabilities reflects management’s estimate of amounts that the Company would have received in connection with the sale of the assets or paid in connection with the transfer of the liabilities in an orderly transaction between market participants at the measurement date. In connection with measuring the fair value of its assets and liabilities, the Company seeks to maximize the use of observable inputs (market data obtained from independent sources) and to minimize the use of unobservable inputs (internal assumptions about how market participants would price assets and liabilities).

The following fair value hierarchy is used to classify assets and liabilities based on the observable inputs and unobservable inputs used in order to value the assets and liabilities:

Level 1: Valuation is based on unadjusted quoted prices in active markets for identical assets and liabilities that are accessible at the reporting date. Because valuations are based on quoted prices that are readily and regularly available in an active market, valuation of these products does not entail a significant degree of judgment.

Level 2: Valuation is determined from pricing inputs that are other than quoted prices in active markets that are either directly or indirectly observable as of the reporting date. Observable inputs include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and interest rates and yield curves that are observable at commonly quoted intervals.

Level 3: Valuation is based on inputs that are both significant to the fair value measurement and unobservable. Level 3 inputs include situations where there is little, if any, market activity for the financial instrument. The inputs into the determination of fair value generally require significant management judgment or estimation.

Liabilities measured at fair value on a recurring basis

The balances of the Company’s liabilities measured at fair value on a recurring basis as of March 31, 2024, are as follows (in thousands):

	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	6	—	—	6
	$6	$—	$—	$6

The balances of the Company’s liabilities measured at fair value on a recurring basis as of December 31, 2023, are as follows (in thousands):

	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	3	—	—	3
	$3	$—	$—	$3

The following is a description of the methodologies used to estimate the fair values of liabilities measured at fair value on a recurring basis and within the fair value hierarchy.

Warrant liabilities

Prior to the business combination, TCAC issued warrants to purchase 10,000,000 Class A ordinary shares at a price of $11.50 per whole share, as part of the units offered by the prospectus for their initial public offering and, simultaneously with the closing of their initial public offering, issued in a private placement an aggregate of 6,000,000 private placement warrants, each exercisable to purchase one Class A ordinary share at a price of $11.50 per share.

The Company utilizes a fair value approach to account for its warrants based on the quoted price at March 31, 2024, the calculation is consistent with ASC 820, Fair Value Measurement, with changes in fair value recorded in current earnings.

At March 31, 2024, the value of the public warrants was approximately $6,400 using a closing price of $0.0004.

Changes in Fair Value

The following tables provides a roll-forward in the changes in fair value in the public warrants for the three months ended March 31, 2024 (in thousands):

Warrants
Balance, January 1, 2024			$3
Change in fair value			3
Balance, March 31, 2024			$6
Changes in fair value included in earnings for the period relating to liabilities held at March 31, 2024			$3

There were no transfers of financial liabilities between levels of the fair value hierarchy during the three months ended March 31, 2024.

Other Fair Value Considerations – Carrying value of accounts receivables, contract assets, prepaid expenses and other assets, accounts payable and accrued expenses approximate fair value due to their short-term maturities and/or low credit risk.

NOTE 18 – FAIR VALUE MEASUREMENTS

The following fair value hierarchy is used to classify assets and liabilities based on the observable inputs and unobservable inputs used in order to value the assets and liabilities:

Liabilities measured at fair value on a recurring basis

The balances of the Company’s liabilities measured at fair value on a recurring basis as of December 31, 2023 and 2022, are as follows (in thousands):

For the year ended December 31, 2022	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	338	—	—	338
	$338	$—	$—	$338

For the year ended December 31, 2023	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	3	—	—	3
	$3	$—	$—	$3

The following is a description of the methodologies used to estimate the fair values of liabilities measured at fair value on a recurring basis and within the fair value hierarchy.

Warrant liabilities

The Company utilizes a fair value approach to account for its warrants based on the quoted price at December 31, 2023, and the calculation is consistent with ASC 820, Fair Value Measurement, with changes in fair value recorded in current earnings.

At December 31, 2023, the value of the public and private warrants was approximately $3,200 using a closing price of $0.0002. At December 31, 2022, the value of the public and private warrants was approximately $0.3 million using a closing price of $0.0211.

Changes in Fair Value

The following tables provides a roll-forward in the changes in fair value for the years ended December 31, 2023 and 2022, for all liabilities for which the Company determines fair value on a recurring basis (in thousands):

Warrants
Balance, January 1, 2022			$—
Assumed in business combination at fair value			$4,496
Change in value			$(4,158)
Balance, December 31, 2022			$338
Changes in fair value included in earnings for the period relating to liabilities held at December 31, 2022			$(4,158)

Balance, January 1, 2023			$338
Change in fair value			(335)
Balance, December 31, 2023			$3
Changes in fair value included in earnings for the period relating to liabilities held at December 31, 2023			$(335)

There were no transfers of financial liabilities between levels of the fair value hierarchy during the year ended December 31, 2023.

Other Fair Value Considerations - Carrying value of accounts receivables, contract assets, prepaid expenses and other assets, accounts payable and accrued expenses approximate fair value due to their short-term maturities and/or low credit risk.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

STOCK BASED COMPENSATION (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Stock Options Outstanding

The following table summarizes information on stock options outstanding as of March 31, 2024 under the Legacy Incentive Plan:

	Options Outstanding		Options Vested and Exercisable
	Number of Options	Weighted Average Exercise Price (Per Share)	Number of Options	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price (Per Share)
Outstanding Balance, January 1, 2024	2,271,894	$0.57	2,244,102	4.76	$0.56
Options granted	—
Options exercised	—	$—
Options forfeited	(2,964)	$1.26
Options cancelled	—	$—
Outstanding Balance, March 31, 2024	2,268,930	$0.57	2,255,034	4.57	$0.57

The following table summarizes information on stock options outstanding as of December 31, 2023 and 2022 under the Legacy Incentive Plan:

	Options Outstanding		Options Vested and Exercisable
Fixed Options	Number of Options	Weighted Average Exercise Price (Per Share)	Number of Options	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price (Per Share)
Outstanding Balance, January 1, 2022	6,802,437	$0.38	4,628,311	6.79	$0.24
Options exercised	(530,666)	$0.55
Options forfeited	(61,460)	$0.75
Options cancelled	(4,791)	$0.75
Outstanding Balance, June 14, 2022	6,205,520
Conversion ratio	0.5929
SpringBig Holdings options	3,679,171
Options exercised	(135,090)	$0.30
Options forfeited	(149,328)	$1.11	______	___	____
Outstanding Balance, January 1, 2023	3,394,753	$0.57	3,250,236	5.79	$0.54
Options exercised	(727,233)	$0.38
Options forfeited	(25,876)	$0.82
Options cancelled	(369,750)	$0.84
Outstanding Balance, Dec. 31, 2023	2,271,894	$0.57	2,244,102	4.76	$0.56

Share-Based Payment Arrangement, Restricted Stock Unit, Activity

The following table summarizes information on Restricted Stock Units outstanding as of March 31, 2024 under the 2022 Incentive Plan:

	Restricted Stock Units Outstanding
	Number of RSUs	Weighted Average Fair Value (Per Share)	Weighted Average Vesting (Years)
Outstanding Balance, December 31, 2022	725,000	$1.97	2.5
RSUs granted	1,989,000	0.56
RSUs forfeited	(276,836)	1.28
RSUs vested and common stock issued	(225,655)	$1.97
Outstanding Balance, December 31, 2023	2,211,509	$0.80
RSUs forfeited	(50,000)	0.80
Outstanding Balance, March 31, 2024	2,161,509	$0.79	1.9

The following table summarizes information on Restricted Stock Units outstanding as of December 31, 2023 under the 2022 Incentive Plan:

	Restricted Stock Units Outstanding
	Number of RSUs	Weighted Average Fair Value (Per Share)	Weighted Average Vesting (Years)
Outstanding Balance, January 1, 2022	—
RSUs granted	761,500	$1.97
RSUs forfeited	(36,500)	$1.97
Outstanding Balance, January 1, 2023	725,000	$1.97	2.5
RSUs granted	1,989,000	$0.56
RSUs forfeited	(276,836)	$1.28
RSUs vested and common stock issued	(225,655)	$1.97
Outstanding Balance, December 31, 2023	2,211,509	$0.80	2.2

BUSINESS COMBINATIONS (FY)

12 Months Ended

Dec. 31, 2023

Reverse Recapitalization Business Combination And Asset Acquisition [Abstract]

BUSINESS COMBINATIONS

NOTE 9 – BUSINESS COMBINATIONS

Reverse Merger

The business combination between Tuatara and Legacy SpringBig was consummated on June 14, 2022. Holders of an aggregate of 19,123,806 Class A ordinary shares of Tuatara sold in its initial public offering properly exercised their right to have such shares redeemed for a full pro rata portion of the trust account holding the proceeds from Tuatara’s IPO, which was approximately $10.01 per share, or $191,437,817 in the aggregate. The holders that did not elect to have their shares redeemed, received, following the domestication, additional shares of common stock which amounted to 876,194 shares of common stock, resulting in total shares of 1,752,388.

Beginning June 15, 2022, the ticker symbols for TCAC’s common stock and warrants were changed to “SBIG” and “SBIGW,” respectively, and commenced trading on The Nasdaq Global Market. The Company received net proceeds of $18.8 million, with gross proceeds of $25.1 million, in addition to the $7.0 million Convertible Notes which were issued in February 2022 and were converted into common stock at the Closing, see Note 10, 15% Convertible Promissory Notes, to these consolidated financial statements for further information. Of the amounts received, approximately $8.8 million represents remaining funds for unredeemed shares from the TCAC trust; $6.1 million from PIPE Financing proceeds and $10.0 million from the Secured Convertible Note. Upon consummation of the Business Combination, Legacy SpringBig options were converted into options of SpringBig as disclosed in Note 16.

On April 29, 2022, the Company entered into the Stock Purchase Agreement with Cantor, which was subsequently amended on July 20, 2022. The Company, in its sole discretion, shall have the right, but not the obligation, to issue and sell to Cantor, and Cantor shall purchase from the Company, up to $50.0 million of common shares, par value $0.0001 per share, subject to certain terms and conditions. During the three months ended September 30, 2022, the Company issued 877,193 shares to satisfy a $1.5 million commitment fee for the Cantor Equity Facility. The Cantor Equity Facility was canceled by the Company on August 30, 2023. No shares were ever sold under the facility.

The following table provides a summary of the significant sources and uses of cash related to the closing of the business combination on June 14, 2022, (in thousands):

Amount available after paying TCAC redeeming stockholders			$8,771
Proceeds from convertible notes			10,000
Proceeds from PIPE Financing			6,100
TCAC operating account			264
Gross proceeds available at closing			25,135
Expenses paid at closing			(6,346)
Net cash to Legacy SpringBig at closing			$18,789
Post closing expense (cash paid or accrued for expenses by Legacy SpringBig)			(8,679)
Net cash after closing			$10,110

The following table provides a reconciliation of the common shares related to the business combination transaction:

TCAC non-redeeming shareholders			1,752,388
PIPE Investors			1,341,356
TCAC sponsor shareholders			4,000,000
Legacy SpringBig shareholders			18,196,526
Issued and outstanding			25,290,270

Of the 1,341,356 shares of common stock shown above, 730,493 shares were issued to holders of the Convertible Note (which was converted at Closing), representing repayment of principal of $7.0 million and outstanding interest of $305,000, in accordance with the terms of the Convertible Notes. See Note 10, 15% Convertible Promissory Note, to these consolidated financial statements for further information.

LEASES - Narrative (Q1) (Details) - USD ($)	1 Months Ended	3 Months Ended		12 Months Ended
LEASES - Narrative (Q1) (Details) - USD ($)	Jun. 30, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Term of contract (in months)	98 months			98 months
Operating lease cost		$ 160,000	$ 133,000	$ 486,000	$ 515,000
Minimum
Lessee, Lease, Description [Line Items]
Monthly rent expense	$ 38,000			38,000
Minimum \| Boca Raton, Florida, Seattle, Washington And Ontario, Canada
Lessee, Lease, Description [Line Items]
Monthly rent expense		4,000		4,000
Maximum
Lessee, Lease, Description [Line Items]
Monthly rent expense	$ 48,000			48,000
Maximum \| Boca Raton, Florida, Seattle, Washington And Ontario, Canada
Lessee, Lease, Description [Line Items]
Monthly rent expense		$ 48,000		$ 7,000

WARRANT LIABILITIES (Q1)	3 Months Ended	12 Months Ended
WARRANT LIABILITIES (Q1)	Mar. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
WARRANT LIABILITIES	NOTE 11 – WARRANT LIABILITIES Prior to the business combination, at the time of their initial public offering, TCAC issued warrants to purchase 10,000,000 Class A ordinary shares at a price of $11.50 per share, for aggregate consideration of $10.0 million as part of the units offered by the prospectus and, simultaneously with the closing of their initial public offering, issued in a private placement an aggregate of 6,000,000 private placement warrants for aggregate consideration of $6.0 million, each exercisable to purchase one Class A ordinary share at a price of $11.50 per share. The Company accounts for the warrants in accordance with the guidance contained in ASC 815 Derivatives and Hedging, under which the warrants do not meet the criteria for equity treatment and hence are recorded as liabilities. Accordingly, we classify the warrants as liabilities at their fair value and adjust the warrants to fair value at each reporting period. This liability is subject to re-measurement at each balance sheet date until exercised, and any change in fair value is recognized in our statement of operations. At March 31, 2024 and December 31, 2023, the estimated fair value of the warrants was $6,400 and $3,200, respectively. The Company recorded a change in fair value loss of approximately $3,000 and $153,000 for the three months ended March 31, 2024 and 2023, respectively. The fair value is determined in accordance with ASC 820, Fair Value Measurement. See Note 17, Fair Value Measurements, to the accompanying condensed consolidated financial statements for further information.	NOTE 12 – WARRANT LIABILITIES Prior to the business combination, at the time of their initial public offering, TCAC issued warrants to purchase 10,000,000 Class A ordinary shares at a price of $11.50 per share, for aggregate consideration of $10.0 million as part of the units offered by the prospectus and, simultaneously with the closing of their initial public offering, issued in a private placement an aggregate of 6,000,000 private placement warrants for aggregate consideration of $6.0 million, each exercisable to purchase one Class A ordinary share at a price of $11.50 per share. The Company accounts for the warrants in accordance with the guidance contained in ASC 815 Derivatives and Hedging, under which the warrants do not meet the criteria for equity treatment and hence are recorded as liabilities. Accordingly, we classify the warrants as liabilities at their fair value and adjust the warrants to fair value at each reporting period. This liability is subject to re-measurement at each balance sheet date until exercised, and any change in fair value is recognized in our statement of operations. At December 31, 2023, the estimated fair value of the warrants was $3,200. At December 31, 2022, the estimated fair value of the warrants is $0.3 million. The Company recorded a change in fair value gain of approximately $0.3 million and $4.2 million for the years ended December 31, 2023 and 2022, respectively. These amounts are included in the statements of operations for the year ended December 31, 2023 and 2022. The fair value is determined in accordance with ASC 820, Fair Value Measurement. See Note 18, Fair Value Measurements, to the accompanying consolidated financial statements for further information.

LONG-TERM DEBT - Schedule of Long-term Debt (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Jan. 23, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Carrying value	$ 8,000		$ 0
Less: Deferred financing fees, net	(802)		0
Total	7,198		0
12% Secured Term Notes, due January 23, 2026 \| Secured Debt
Debt Instrument [Line Items]
Carrying value	1,600		0
Interest rate (as percent)		12.00%
8% Secured Convertible Notes, due January 23, 2026 \| Convertible Debt
Debt Instrument [Line Items]
Carrying value	$ 6,400		$ 0
Interest rate (as percent)		8.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

6% SENIOR SECURED CONVERTIBLE NOTES (Q1)	3 Months Ended	12 Months Ended
6% SENIOR SECURED CONVERTIBLE NOTES (Q1)	Mar. 31, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
6% SENIOR SECURED CONVERTIBLE NOTES	NOTE 10 – 6% SENIOR SECURED CONVERTIBLE NOTES In connection with the business combination, on June 14, 2022, the Company issued $11.0 million in aggregate principal amount of Senior Secured Original Issue Discount Convertible Note, due June 14, 2024 (the “Secured Convertible Notes”), issued at a discount of $1.0 million, with proceeds of $10.0 million received on the Closing Date. A warrant representing 586,890 shares of common stock of the Company (the “Convertible Warrant”) with a fair value of $839,000 as at the date of the business combination was also issued in a private placement with the purchaser party thereto. To determine the fair value of the Convertible Warrant, the Company performed a Black-Scholes calculation as of June 14, 2022 using a stock price of $4.28, a strike price of $12.00, a risk free rate of 3.61%, annualized volatility of 65%, and a time to maturity of five years. On January 16, 2024, the Company and the noteholder executed an agreement for the Company to repurchase the outstanding note and associated warrants, and on January 23, 2024, the note and associated warrants were repurchased for $2.9 million. As such, the outstanding principal on the Secured Convertible Notes at March 31, 2024 was $0. At December 31, 2023, the outstanding principal of the Secured Convertible Notes was $5.1 million with a carrying value of $4.4 million, net of discount of $0.7 million. The Company recorded a $1.6 million gain on repurchase of the note for the three months ended March 31, 2024. The Company recorded $14,000 and $402,000 of interest expense in connection with the Senior Secured Convertible Notes for the three months ended March 31, 2024 and March 31, 2023, respectively.	NOTE 10 – 15% CONVERTIBLE PROMISSORY NOTES In February 2022, the Company issued $7.0 million in aggregate principal amount of convertible promissory notes due September 30, 2022 (the “Convertible Notes”). The Convertible Notes accrued interest at the rate of 15% per annum on the principal amount of the Convertible Notes, due and payable at the maturity date of September 30, 2022 (the “Maturity Date”), if not converted prior to the maturity date. Under the terms of such notes, the conversion of the Convertible Notes could be triggered by the closing of the business combination between Tuatara and Legacy SpringBig, the occurrence of the stated maturity date, or in connection with certain equity issuances. The Convertible Notes contained customary events of default such as failures to observe or perform any covenants, obligation, condition or agreement contained in the Convertible Notes and commencement of bankruptcy. In connection with the consummation of the business combination, the Convertible Notes and outstanding accrued interest converted in full into 730,493 shares of common stock at a price of $10.00 per share, representing repayment of principal of $7.0 million and outstanding interest of $305,000, in accordance with the terms of the Convertible Notes. During the year ended December 31, 2022, the Company recorded $305,000 of interest expense on the Convertible Notes, respectively.

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 470
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//470/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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STOCK BASED COMPENSATION - Narrative (Q1) (Details) - USD ($)			3 Months Ended		7 Months Ended	12 Months Ended
	Jan. 01, 2024	Jun. 14, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Jun. 13, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)			1,525,175
Percentage of amount of shares of common stock			5.00%
Share-based compensation expense		$ 900,000
Exercise of stock options (in shares)			0		135,090	727,233
Options vested and exercisable (in shares)			2,255,034		3,250,236	2,244,102	3,250,236
Options outstanding and exercisable, intrinsic value			$ 0
Cost not yet recognized			$ 17,000
Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Recognition period (in years)			3 months
Restricted Stock Units (RSUs)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Cost not yet recognized			$ 1,100,000
Restricted Stock \| Tranche One
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights percentage			33.00%			33.00%
Restricted Stock \| Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights percentage			33.00%			33.00%
Restricted Stock \| Tranche Three
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights percentage			33.00%			33.00%
2022 Long-Term Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)						1,525,175
Percentage of amount of shares of common stock						5.00%	5.00%
Issuance of common stock (in shares)								1,332,986
Additional shares authorized (in shares)	2,266,988
Common stock, authorized for issuance (in shares)			5,125,149
Share-based compensation expense						$ 704,000	$ 246,000
Cost not yet recognized						1,336,000
Legacy Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation expense			$ 17,000	$ 30,000		118,000	$ 982,000
Cost not yet recognized						$ 35,000
2023 Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation expense			$ 178,000	$ 132,000

STOCK BASED COMPENSATION - Narrative (FY) (Details) - USD ($)		3 Months Ended		12 Months Ended
	Jun. 14, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Jun. 13, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Intrinsic value of options exercised				$ 162,000	$ 3,400,000
Share-based payment award, options, non-vested (in shares)	192,689
Share-based compensation expense	$ 900,000
Cost not yet recognized		$ 17,000
Common stock, capital shares reserved for future issuance (in shares)		1,525,175
Percentage of amount of shares of common stock		5.00%
Restricted Stock \| Tranche One
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights percentage		33.00%		33.00%
Restricted Stock \| Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights percentage		33.00%		33.00%
Restricted Stock \| Share-Based Payment Arrangement, Tranche Three
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights percentage		33.00%		33.00%
Legacy Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation expense		$ 17,000	$ 30,000	$ 118,000	982,000
Intrinsic value of remaining options				0
Cost not yet recognized				35,000
2022 Long-Term Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation expense				$ 704,000	$ 246,000
Common stock, capital shares reserved for future issuance (in shares)				1,525,175
Percentage of amount of shares of common stock				5.00%	5.00%
Additional shares reserved for issuance (in shares)						1,332,986
Unrecognized expense				$ 1,336,000

BUSINESS COMBINATIONS - Schedule Of Share Transactions In Reverse Recapitalization (FY) (Details) - shares	Jun. 14, 2022	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Schedule Of Reverse Recapitalization [Line Items]
Common stock, shares, issued (in shares)	25,290,270	45,594,864	45,339,762	26,940,841	26,659,711
Common stock, shares, outstanding (in shares)	25,290,270	45,594,864	45,339,762	26,940,841	26,659,711
TCAC non-redeeming shareholders
Schedule Of Reverse Recapitalization [Line Items]
Issue of common stock (in shares)	1,752,388
PIPE Investors
Schedule Of Reverse Recapitalization [Line Items]
Issue of common stock (in shares)	1,341,356
TCAC sponsor shareholders
Schedule Of Reverse Recapitalization [Line Items]
Issue of common stock (in shares)	4,000,000
Legacy SpringBig shareholders
Schedule Of Reverse Recapitalization [Line Items]
Issue of common stock (in shares)	18,196,526
Common stock, shares, issued (in shares)	8,362,933
Common stock, shares, outstanding (in shares)	8,362,933

ACCRUED EXPENSES AND OTHER LIABILITIES (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

ACCRUED EXPENSES AND OTHER LIABILITIES

NOTE 7 – ACCRUED EXPENSES AND OTHER LIABILITIES

Accrued expenses and other current liabilities consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Accrued wages, commission and bonus	$270	$393
Accrued professional fees	95	176
Deferred financial advisory fees	1,000	1,000
Other liabilities	402	382
	$1,767	$1,951

NOTE 7 – ACCRUED EXPENSES AND OTHER LIABILITIES

Accrued expenses and other current liabilities consisted of the following (in thousands):

	December 31,
	2023	2022
Accrued wages, commission and bonus	$393	$1,145
Accrued professional fees	176	148
Deferred financial advisory fees	1,000	1,000
Other liabilities	382	261
	$1,951	$2,554

NET INCOME (LOSS) PER SHARE (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Reconciliation of Actual Basic and Diluted Earnings Per Share

The following table reconciles actual basic and diluted income (loss) per share for the three months ended March 31, 2024 and 2023, respectively (in thousands, except share and per share data).

	Three Months Ended March 31,
	2024	2023
Numerator:
Net income (loss) for basic net income (loss) calculation	$417	$(2,262)
Effect of dilutive securities:
Interest expense on Convertible Notes	85	—
Net income (loss) for diluted net income (loss) calculation	$502	$(2,262)

	Three Months Ended March 31,
	2024	2023
Denominator
Denominator for basic net income (loss) per share, weighted average	45,432,272	26,803,839
Effect of dilutive securities:
Convertible notes stock conversion, weighted average as converted	31,882,784	—
Denominator for diluted net income per share	77,315,056	26,803,839
Net income (loss) per common share
Basic	$0.01	$(0.08)
Diluted	$0.01	$(0.08)

The following table reconciles actual basic and diluted earnings per share for the years ended December 31, 2023 and 2022, respectively (in thousands, except share and per share data).

	Years Ended December 31,
	2023	2022
Loss per share:
Numerator:
Net loss	$(10,233)	$(13,076)
Denominator
Weighted-average common shares outstanding
Basic and diluted	36,147,187	22,287,828
Net loss per common share
Basic and diluted	$(0.28)	$(0.59)

Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share

The anti-dilutive securities excluded from the weighted-average shares used to calculate the diluted net income per common share for the three months ended March 31, 2024 and the net loss per common share for the three months ended March 31, 2023 were as follows:

	Three Months Ended March 31,
	2024	2023
Shares unvested and subject to exercise of stock options	13,896	120,431
Shares subject to outstanding common stock options	2,255,034	2,945,020
Shares subject to convertible notes stock conversion	—	695,261
Shares subject to warrants stock conversion	16,000,000	16,586,980
Shares subject to contingent earn out	10,500,000	10,500,000
Restricted stock units	2,161,509	1,314,000

The anti-dilutive securities excluded from the weighted-average shares used to calculate the diluted net loss per common share for the years ended December 31, 2023 and 2022 were as follows:

	Years Ended December 31,
	2023	2022
Shares unvested and subject to exercise of stock options	27,792	144,517
Shares subject to outstanding common stock options	2,244,102	3,250,236
Shares subject to convertible notes stock conversion	5,111,929	816,667
Shares subject to warrants stock conversion	16,586,980	16,586,980
Shares subject to contingent earn out	10,500,000	10,500,000
Restricted stock units	2,211,509	725,000

15% CONVERTIBLE PROMISSORY NOTES (FY)	3 Months Ended	12 Months Ended
15% CONVERTIBLE PROMISSORY NOTES (FY)	Mar. 31, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
15% CONVERTIBLE PROMISSORY NOTES	NOTE 10 – 6% SENIOR SECURED CONVERTIBLE NOTES In connection with the business combination, on June 14, 2022, the Company issued $11.0 million in aggregate principal amount of Senior Secured Original Issue Discount Convertible Note, due June 14, 2024 (the “Secured Convertible Notes”), issued at a discount of $1.0 million, with proceeds of $10.0 million received on the Closing Date. A warrant representing 586,890 shares of common stock of the Company (the “Convertible Warrant”) with a fair value of $839,000 as at the date of the business combination was also issued in a private placement with the purchaser party thereto. To determine the fair value of the Convertible Warrant, the Company performed a Black-Scholes calculation as of June 14, 2022 using a stock price of $4.28, a strike price of $12.00, a risk free rate of 3.61%, annualized volatility of 65%, and a time to maturity of five years. On January 16, 2024, the Company and the noteholder executed an agreement for the Company to repurchase the outstanding note and associated warrants, and on January 23, 2024, the note and associated warrants were repurchased for $2.9 million. As such, the outstanding principal on the Secured Convertible Notes at March 31, 2024 was $0. At December 31, 2023, the outstanding principal of the Secured Convertible Notes was $5.1 million with a carrying value of $4.4 million, net of discount of $0.7 million. The Company recorded a $1.6 million gain on repurchase of the note for the three months ended March 31, 2024. The Company recorded $14,000 and $402,000 of interest expense in connection with the Senior Secured Convertible Notes for the three months ended March 31, 2024 and March 31, 2023, respectively.	NOTE 10 – 15% CONVERTIBLE PROMISSORY NOTES In February 2022, the Company issued $7.0 million in aggregate principal amount of convertible promissory notes due September 30, 2022 (the “Convertible Notes”). The Convertible Notes accrued interest at the rate of 15% per annum on the principal amount of the Convertible Notes, due and payable at the maturity date of September 30, 2022 (the “Maturity Date”), if not converted prior to the maturity date. Under the terms of such notes, the conversion of the Convertible Notes could be triggered by the closing of the business combination between Tuatara and Legacy SpringBig, the occurrence of the stated maturity date, or in connection with certain equity issuances. The Convertible Notes contained customary events of default such as failures to observe or perform any covenants, obligation, condition or agreement contained in the Convertible Notes and commencement of bankruptcy. In connection with the consummation of the business combination, the Convertible Notes and outstanding accrued interest converted in full into 730,493 shares of common stock at a price of $10.00 per share, representing repayment of principal of $7.0 million and outstanding interest of $305,000, in accordance with the terms of the Convertible Notes. During the year ended December 31, 2022, the Company recorded $305,000 of interest expense on the Convertible Notes, respectively.

SENIOR SECURED CONVERTIBLE NOTES (FY) (Details)					1 Months Ended	3 Months Ended		12 Months Ended
SENIOR SECURED CONVERTIBLE NOTES (FY) (Details)	Jan. 23, 2024 USD ($)	Jan. 16, 2024 USD ($)	Sep. 05, 2023	Jun. 14, 2022 USD ($) $ / shares	Feb. 28, 2022 USD ($)	Mar. 31, 2024 USD ($) shares	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($)	May 25, 2023 $ / shares
Debt Instrument [Line Items]
Proceeds from convertible notes					$ 7,000,000	$ 6,400,000	$ 0	$ 0	$ 7,000,000
Carrying value						8,000,000		0
Interest expense						875,000	391,000	2,247,000	949,000
Repayment of convertible debt	$ 2,900,000					$ 2,895,000	1,457,000	$ 3,238,000	1,000,000
Subsequent Event
Debt Instrument [Line Items]
Repayment of convertible debt	2,900,000
Secured Convertible Notes
Debt Instrument [Line Items]
Conversion price per share (in dollars per shares) \| $ / shares				$ 12						$ 1
Volume-weighted average price				93.00%
Warrants outstanding (in shares) \| shares						586,890		586,890
Warrants and rights outstanding						$ 839,000		$ 839,000
Maturity term				5 years
Secured Convertible Notes \| Measurement Input, Share Price
Debt Instrument [Line Items]
Convertible warrants, measurement input				4.28
Secured Convertible Notes \| Measurement Input, Conversion Price
Debt Instrument [Line Items]
Convertible warrants, measurement input				12
Secured Convertible Notes \| Measurement Input, Risk Free Interest Rate
Debt Instrument [Line Items]
Convertible warrants, measurement input				0.0361
Secured Convertible Notes \| Measurement Input, Price Volatility
Debt Instrument [Line Items]
Convertible warrants, measurement input				0.65
Convertible Notes Payable
Debt Instrument [Line Items]
Proceeds from convertible notes				$ 10,000,000
Senior Secured Original Issue Discount Convertible Note \| Convertible Notes Payable
Debt Instrument [Line Items]
Discount issued on convertible notes								700,000	1,500,000
Interest rate						6.00%
Percentage of principal amount of convertible notes			115.00%
Debt default conversion ratio			0.8
Carrying value						$ 0		5,100,000	9,800,000
Long-term debt, non-current								4,400,000	8,300,000
Interest expense						14,000	$ 402,000	402,000	$ 356,000
Senior Secured Original Issue Discount Convertible Note \| Convertible Notes Payable \| Subsequent Event
Debt Instrument [Line Items]
Repayment of convertible debt	2,900,000	$ 2,900,000
Tranche One \| Convertible Notes Payable
Debt Instrument [Line Items]
Aggregate principal amount				11,000,000
Discount issued on convertible notes				$ 1,000,000
Interest rate				6.00%
Interest payment grace period				6 months
8.00% Convertible Notes \| Convertible Debt
Debt Instrument [Line Items]
Aggregate principal amount	$ 6,400,000
Interest rate	8.00%
Carrying value						$ 6,400,000		$ 0
8.00% Convertible Notes \| Convertible Debt \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 6,400,000
Interest rate	8.00%	8.00%

BENEFIT PLAN (FY) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
BENEFIT PLAN (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Postemployment Benefits [Abstract]
Company matching contributions	$ 96	$ 158	$ 529	$ 502

BENEFIT PLAN (FY)	3 Months Ended	12 Months Ended
BENEFIT PLAN (FY)	Mar. 31, 2024	Dec. 31, 2023
Postemployment Benefits [Abstract]
BENEFIT PLAN	NOTE 20 – BENEFIT PLAN The Company maintains a safe harbor 401(k) retirement plan for the benefit of its employees. The plan allows participants to make contributions subject to certain limitations. Company matching contributions were $96,000 and $158,000 for the three months ended March 31, 2024 and 2023, respectively.	NOTE 21 – BENEFIT PLAN The Company maintains a safe harbor 401(k) retirement plan for the benefit of its employees. The plan allows participants to make contributions subject to certain limitations. Company matching contributions were $529,000 and $502,000 for the years ended December 31, 2023 and 2022, respectively.

The entire disclosure for retirement benefits.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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ACCOUNTS RECEIVABLE - Schedule of Accounts Receivable (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Receivables [Abstract]
Accounts receivable	$ 4,005	$ 3,690	$ 3,639
Unbilled receivables	854	853	731
Total receivables	4,859	4,543	4,370
Less allowance for credit losses	(1,648)	(1,595)	(1,481)
Accounts receivable, net	$ 3,211	$ 2,948	$ 2,889

LEASES (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Supplemental Balance Sheet Information

As of March 31, 2024, and December 31, 2023, the following amounts were presented on the Company’s condensed consolidated balance sheets in accordance with ASC 842 - Lease Accounting (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Balance Sheet
Assets:
Right of use asset - operating lease	$3,031	$340
Liabilities
Current	329	99
Non-current	2,815	225
Total operating lease liability	$3,144	$324

As of December 31, 2023, the following amounts were presented on SpringBig’s consolidated balance sheets in accordance with the Leasing Standard.

	Year ended December 31,
	2023	2022
Balance Sheet
Assets:
Right of Use Assets - Operating Lease	$340	$750
Liabilities:
Current	99	465
Non-current	225	316
Total Operating Lease Liabilities	$324	$781

Schedule of Lease Cost and Other Information

Other information pertaining to capitalized assets and liabilities under the leasing standard is as follows (in thousands):

	Three Months Ended March 31, 2024	Three Months Ended March 31, 2023
Other information
Operating lease cost	$160	$133
Operating cash flows paid to operating leases	$31	$126
Right-of-use assets in exchange for new operating lease liabilities	$2,781	$—
Weighted-average remaining lease term — operating leases (months)	89.9	17.9
Weighted-average discount rate — operating leases	9.05%	5.67%

Other information pertaining to capitalized assets and liabilities under the leasing standard is as follows.

	2023	2022
Other information
Operating lease cost	$486	$515
Operating cash flows from operating leases	$520	$318
Disposal of right-of-use assets	$299	$—
Disposal of operating lease liabilities associated with right-of-use assets	$313	$—
Right-of-use assets obtained in exchange for new operating lease liabilities	$412	$150
Weighted-average remaining lease term - operating leases (months)	35.1	20.4
Weighted-average discount rate - operating leases	9%	6%

Schedule of Lease Liabilities Maturity

As of March 31, 2024, the Company’s lease liabilities mature as follows:

Fiscal Year:			Operating Leases
2024			$434
2025			595
2026			592
2027			504
Thereafter			2,278
Total lease payments			4,403
Less Imputed Interest			(1,259)
Present value of lease liabilities			$3,144

As of December 31, 2023, the Company’s lease liabilities mature as follows:

			Operating Leases
Fiscal Year:
2024			$124
2025			128
2026			110
2027			9
Total lease payments			371
Less imputed interest			(47)
Present value of lease liabilities			$324

ACCOUNTS RECEIVABLE (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Accounts Receivable

Accounts receivable, net consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Accounts receivable	$4,005	$3,690
Unbilled receivables	854	853
Total receivables	4,859	4,543
Less allowance for doubtful accounts	(1,648)	(1,595)
Accounts receivable, net	$3,211	$2,948

Accounts receivable, net consisted of the following (in thousands):

	December 31,
	2023	2022
Accounts receivable	$3,690	$3,639
Unbilled receivables	853	731
Total receivables	4,543	4,370
Less allowance for credit losses	(1,595)	(1,481)
Accounts receivable, net	$2,948	$2,889

Schedule of Allowance for Credit Loss

The following table details the activity related to the Company’s allowance for credit losses for the quarter ending March 31, 2024 (in thousands).

			Allowance for credit losses
Outstanding Balance, December 31, 2023			$1,595
Current-period provision (release) for expected credit losses			53
Write-offs charged against the allowance, net of recoveries and other			—
Outstanding Balance, March 31, 2024			$1,648

The following table details the activity related to the Company’s allowance for credit losses for the years ending December 31, 2023 and 2022, respectively (in thousands).

			Allowance for credit losses
Outstanding Balance, January 1, 2023			$1,481
Current-period provision (release) for expected credit losses			1,563
Write-offs charged against the allowance, net of recoveries and other			(1,449)
Outstanding Balance, December 31, 2023			$1,595

STOCKHOLDERS EQUITY (FY) (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Schedule of Stock Issued and Outstanding

With the consummation of the business combination, Legacy SpringBig. issued and outstanding shares were converted into shares of SpringBig common stock as follows:

	Legacy SpringBig	Conversion Rate	SpringBig
Series B Preferred	4,585,202	0.59289	2,718,522
Series A Preferred	5,088,944	0.59289	3,017,184
Series Seed Preferred	6,911,715	0.59289	4,097,887
Common Stock	14,105,371	0.59289	8,362,933
	30,691,232		18,196,526

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

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Schedule of U.S. and Foreign Components of Loss From Operations Before Income Taxes

CONTRACT ASSETS AND LIABILITIES - Schedule of Contract with Customer, Contract Asset, Contract Liability, and Receivable (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Contract assets consisted of the following as of:
Deferred sales commissions	$ 255	$ 273	$ 333
Contract liabilities consisted of the following as of
Deferred revenue	$ 2	0	291	$ 450
Retail revenue
Contract liabilities consisted of the following as of
Deferred revenue		0	277
Brand revenue
Contract liabilities consisted of the following as of
Deferred revenue		$ 0	$ 14

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (FY) (Details) $ / shares in Units, $ in Thousands			3 Months Ended		12 Months Ended
	Jan. 23, 2024 USD ($) $ / shares	Jan. 16, 2024 USD ($)	Mar. 31, 2024 USD ($) segment	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)
Product Information [Line Items]
Accumulated deficit			$ 36,148		$ 36,565	$ 26,332
Net cash used in operating activities			1,878	$ (379)	3,976	14,518
Working capital deficit			(1,400)		(9,100)
Cash and cash equivalents			1,668		331	3,546
Purchase obligation	$ 2,900		$ 2,895	$ 1,457	$ 3,238	1,000
Number of operating segments \| segment			1		1
Number of reportable segments \| segment			1		1
Contract assets amortization period					3 years
Property and equipment, useful life			3 years		3 years
Impairment loss					$ 116	0
Estimated useful life					3 years
Advertising expense					$ 36	$ 174
Convertible Note Receivable, Accrued Interest
Product Information [Line Items]
Impairment loss					$ 272
8.00% Convertible Notes \| Convertible Debt
Product Information [Line Items]
Aggregate principal amount	$ 6,400
Interest rate	8.00%
Maturity term	2 years
Conversion price (dollars per share) \| $ / shares	$ 0.15
Term Note \| Secured Debt
Product Information [Line Items]
Aggregate principal amount	$ 1,600
Interest rate	12.00%
Maturity term	2 years
Senior Secured Original Issue Discount Convertible Note \| Convertible Notes Payable
Product Information [Line Items]
Interest rate			6.00%
Subsequent Event
Product Information [Line Items]
Purchase obligation	$ 2,900
Subsequent Event \| 8.00% Convertible Notes \| Convertible Debt
Product Information [Line Items]
Aggregate principal amount	$ 6,400
Interest rate	8.00%	8.00%
Maturity term	2 years
Conversion price (dollars per share) \| $ / shares	$ 0.15
Subsequent Event \| Term Note \| Secured Debt
Product Information [Line Items]
Aggregate principal amount	$ 1,600
Interest rate	12.00%
Maturity term	2 years
Subsequent Event \| Senior Secured Original Issue Discount Convertible Note \| Convertible Notes Payable
Product Information [Line Items]
Purchase obligation	$ 2,900	$ 2,900
Software
Product Information [Line Items]
Property and equipment, useful life					3 years
Cost of Goods and Service Benchmark \| Supplier Concentration Risk \| One Vendor
Product Information [Line Items]
Concentration risk, percentage			60.00%	75.00%	86.00%
Cost of Goods and Service Benchmark \| Supplier Concentration Risk \| Two Vendor
Product Information [Line Items]
Concentration risk, percentage						86.00%
Accounts Payable \| Supplier Concentration Risk \| One Vendor
Product Information [Line Items]
Concentration risk, percentage			26.00%
Accounts Payable \| Supplier Concentration Risk \| Two Vendor
Product Information [Line Items]
Concentration risk, percentage				30.00%	30.00%
Accounts Payable \| Supplier Concentration Risk \| Three Vendor
Product Information [Line Items]
Concentration risk, percentage						54.00%
One Customer \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Product Information [Line Items]
Concentration risk, percentage			14.00%	12.00%	14.00%	11.00%
One Customer \| Accounts Receivable \| Customer Concentration Risk
Product Information [Line Items]
Concentration risk, percentage						12.00%
Two Customer \| Accounts Receivable \| Customer Concentration Risk
Product Information [Line Items]
Concentration risk, percentage					30.00%

STOCK BASED COMPENSATION - Stock Options Outstanding (Q1) (Details) - $ / shares	3 Months Ended	7 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Number of Options
Outstanding beginning balance (in shares)	2,271,894	3,679,171	3,394,753
Options granted (in shares)	0
Options exercised (in shares)	0	(135,090)	(727,233)
Options forfeited (in shares)	(2,964)	(149,328)	(25,876)
Options cancelled (in shares)	0		(369,750)
Outstanding ending balance (in shares)	2,268,930	3,394,753	2,271,894	3,394,753
Weighted Average Exercise Price (Per Share)
Outstanding beginning balance (in dollars per share)	$ 0.57		$ 0.57
Options exercised (in dollars per share)	0	$ 0.3	0.38
Options forfeited (in dollars per share)	1.26	1.11	0.82
Options cancelled (in dollars per share)	0		0.84
Outstanding ending balance (in dollars per share)	$ 0.57	$ 0.57	$ 0.57	$ 0.57
Options Vested and Exercisable, Number Of Options (in shares)	2,255,034	3,250,236	2,244,102	3,250,236
Options Vested and Exercisable, Weighted Average Remaining Contractual Life (Years)	4 years 6 months 25 days		4 years 9 months 3 days	5 years 9 months 14 days
Options Vested and Exercisable, Weighted Average Exercise Price (Per Share)	$ 0.57	$ 0.54	$ 0.56	$ 0.54

ACCOUNTS RECEIVABLE - Schedule of Allowance for Credit Loss (Q1) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit loss, beginning balance	$ 1,595	$ 1,481
Current-period provision (release) for expected credit losses	53	1,563
Write-offs charged against the allowance, net of recoveries and other	0	(1,449)
Allowance for credit loss, ending balance	$ 1,648	$ 1,595

INCOME TAXES (FY) (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

U.S. and foreign components of loss from operations before income taxes were as follows (in thousands):

Schedule of Components of Income Tax Expense (Benefit)

The provision (benefit) for income taxes consist of the following, (in thousands):

	Years Ended December 31,
	2023	2022
Provision (benefit) for income taxes
Current
Federal	$—	$—
State	4	1
International	—	2
	$4	$ 3

Schedule of Effective Income Tax Rate Reconciliation

The Company’s actual provision (benefit) for income taxes from operations differ from the federal expected income tax provision as follows (in thousands):

	December 31, 2023		December 31, 2022
	Amount	Rate	Amount	Rate
U.S. federal income tax provision (benefit) at statutory rate	$(2,126)	21%	$(2,754)	21%
Increase (decrease) in taxes resulting from:
State income tax expense	4	5%	1	5%
Foreign income and losses taxed at different rates	(28)	1%	(68)	1%
Change in valuation allowance	2,090	(32)%	4,122	(32)%
Non-deductible or non-taxable items	37	5%	(1,302)	5%
Foreign income taxes	—	—%	2	—%
Effect of income tax rate changes on deferred items	27	—%	2	—%
Provision (benefit) for income taxes	$4	—%	$3	—%

Schedule of Deferred Tax Assets and Liabilities

The tax effects of temporary difference that give rise to a significant portion of deferred tax assets and tax liabilities for the years ended December 31, 2023 and 2022 are as follows (in thousands):

	Years Ended December 31,
	2023	2022
Deferred tax assets:
Accrued expenses and other liabilities	$771	$376
Net operating loss - US Federal	4,848	5,556
Net operating loss - US State	1,020	1,188
Net operating loss - Foreign	711	575
Property and equipment, net	—	8
Operating lease liability	82	198
Research and development	1,974	—
Stock based compensation	525	215
Total gross deferred tax assets	$9,931	$8,116
Less: valuation allowance	(9,596)	(7,506)
Total deferred tax assets	335	610
Deferred tax liabilities:
Prepaid expenses and other assets	$(231)	$(420)
Operating lease right of use asset	(79)	(190)
Property and equipment, net	(25)	—
Total deferred tax liabilities	(335)	(610)
Net deferred income tax asset (liability)	$—	$—

RELATED PARTY TRANSACTIONS (FY) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Technology and software development	$ 1,666	$ 2,300	$ 8,011	$ 11,353
Related party repayments	540	0	522	0
Current liabilities	7,084		13,551	9,817
Majority Shareholder
Related Party Transaction [Line Items]
Technology and software development	2	$ 4	13	153
Accounts payable	$ 2		2	$ 3
Mr. Harris, CEO
Related Party Transaction [Line Items]
Loan amount			1,000
Related party repayments			500
Current liabilities			$ 500

Total obligations incurred as part of normal operations that are expected to be paid during the following twelve months or within one business cycle, if longer.

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-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 19: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 852
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481404/852-10-50-7

Reference 20: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 852
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481404/852-10-50-7

Reference 21: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.21)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

REVENUE RECOGNITION (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Disaggregation of Revenue

The following table represents our revenues disaggregated by type (in thousands):

	Three Months Ended March 31,
	2024	2023
Revenue
Brand revenue	$59	$295
Retail revenue	6,415	6,862
Total revenue	$6,474	$7,157

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Three Months Ended March 31,
	2024	2023
Brand revenue
United States	$59	$294
Canada	—	1
Retail revenue
United States	6,273	6,663
Canada	142	199
	$6,474	$7,157

The following table represents our revenues disaggregated by type (in thousands):

	Year ended December 31,
	2023	2022
Revenue
Brand revenue	$901	$940
Retail revenue	27,149	25,689
Total Revenue	$28,050	$26,629

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Year ended December 31,
	2023	2022
Brand revenue
United States	$889	$936
Canada	12	4
Retail revenue
United States	26,372	25,075
Canada	777	614
	$28,050	$26,629

REVENUE RECOGNITION (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

REVENUE RECOGNITION

NOTE 12 – REVENUE RECOGNITION

The following table represents our revenues disaggregated by type (in thousands):

	Three Months Ended March 31,
	2024	2023
Revenue
Brand revenue	$59	$295
Retail revenue	6,415	6,862
Total revenue	$6,474	$7,157

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Three Months Ended March 31,
	2024	2023
Brand revenue
United States	$59	$294
Canada	—	1
Retail revenue
United States	6,273	6,663
Canada	142	199
	$6,474	$7,157

Revenues by geography are generally based on the country of the Company’s contracting entity. Total United States revenue was approximately 98% of total revenue for the three months ended March 31, 2024 and 97% for the three months ended March 31, 2023.

NOTE 13 – CONTRACT ASSETS AND LIABILITIES

Contract assets consisted of the following as of (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Deferred sales commissions	$255	$273

The movement in the contract assets during the three months ended March 31, 2024 and the year ended December 31, 2023, comprised the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Contract assets at start of the period	$273	$333
Expense deferred during the period	36	165
(Less) amounts expensed during the period	(54)	(225)
Contract assets at end of the period	$255	$273

NOTE 13 – REVENUE RECOGNITION

The following table represents our revenues disaggregated by type (in thousands):

	Year ended December 31,
	2023	2022
Revenue
Brand revenue	$901	$940
Retail revenue	27,149	25,689
Total Revenue	$28,050	$26,629

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Year ended December 31,
	2023	2022
Brand revenue
United States	$889	$936
Canada	12	4
Retail revenue
United States	26,372	25,075
Canada	777	614
	$28,050	$26,629

Revenues by geography are generally based on the country of the Company’s contracting entity. Total United States revenue was approximately 97% of total revenue for the year ended December 31, 2023 and 98% of total revenue for the year ended December 31, 2022.

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-9

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-10

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-15

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

CONTRACT ASSETS AND LIABILITIES - Contract Assets (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Deferred sales commissions	$ 255	$ 273	$ 333

COMMITMENTS AND CONTINGENCIES (FY)	3 Months Ended	12 Months Ended
COMMITMENTS AND CONTINGENCIES (FY)	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE 16 – COMMITMENTS AND CONTINGENCIES Litigation The Company is from time to time involved in litigation incidental to the conduct of its business. In accordance with applicable accounting guidance, the Company records a provision for a liability when it is both probable that a liability has been incurred and the amount can be reasonably estimated. Management believes that the outcome of such legal proceedings, legal actions and claims will not have a significant adverse effect on the Company’s financial position, results of operations or cash flows. Employee Retention Payroll Tax Credits In March 2020, the U.S. government enacted the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) to provide economic and other relief as a result of the COVID-19 pandemic. The CARES Act includes, among other items, provisions relating to refundable employee retention payroll tax credits. Due to the complex nature of the employee retention credit computations, any benefits we may receive are uncertain and may significantly differ from our current estimates. We plan to record any benefit related to these credits upon both the receipt of the benefit and the resolution of the uncertainties, including, but not limited to, the completion of any potential audit or examination, or the expiration of the related statute of limitations. During the three months ended March 31, 2023, we received $2.0 million related to these credits, recognized $0.6 million as an offset related to operating expenses thorough accounts payable, and we have deferred recognition of remaining $1.4 million, which is recorded in current liabilities on the accompanying condensed consolidated balance sheets.	NOTE 16 – COMMITMENTS AND CONTINGENCIES Employment Agreements The Company has entered into employment agreements with Jeffrey Harris, CEO of SpringBig, and Paul Sykes, CFO of SpringBig, which became effective as of the consummation of the business combination. Litigation The Company evaluates the possible resolution of any legal and other contingencies when losses are possible in accordance with ASC 450, Contingencies (“ASC 450”). Significant judgment is required in both the determination of the probability of an outcome as well as the determination of an estimate of the amount of any potential loss. During the year ended December 31, 2023, the Company settled a dispute concerning the granting in 2017 of a non-exclusive, perpetual license to install and use certain of the Company’s software and derivative works, subject to certain limitations. As a result of the settlement, the Company recorded a liability of approximately $0.8 million. As of December 31, 2023, the Company has settled a portion of this liability through cash payments of $0.2 million and an equity issuance of $0.3 million. The remaining $0.3 million will be paid in equal installments of $40,000 on the last day of each month until the balance is settled in full by July 2024. The Company is from time to time involved in litigation incidental to the conduct of its business. In accordance with applicable accounting guidance, the Company records a provision for a liability when it is both probable that a liability has been incurred and the amount can be reasonably estimated. Management, after consulting legal counsel, believes that the outcome of such legal proceedings, legal actions and claims will not have a significant adverse effect on the Company’s financial position, results of operations or cash flows.

REVENUE RECOGNITION (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

REVENUE RECOGNITION

NOTE 12 – REVENUE RECOGNITION

The following table represents our revenues disaggregated by type (in thousands):

	Three Months Ended March 31,
	2024	2023
Revenue
Brand revenue	$59	$295
Retail revenue	6,415	6,862
Total revenue	$6,474	$7,157

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Three Months Ended March 31,
	2024	2023
Brand revenue
United States	$59	$294
Canada	—	1
Retail revenue
United States	6,273	6,663
Canada	142	199
	$6,474	$7,157

NOTE 13 – CONTRACT ASSETS AND LIABILITIES

Contract assets consisted of the following as of (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Deferred sales commissions	$255	$273

The movement in the contract assets during the three months ended March 31, 2024 and the year ended December 31, 2023, comprised the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Contract assets at start of the period	$273	$333
Expense deferred during the period	36	165
(Less) amounts expensed during the period	(54)	(225)
Contract assets at end of the period	$255	$273

NOTE 13 – REVENUE RECOGNITION

The following table represents our revenues disaggregated by type (in thousands):

	Year ended December 31,
	2023	2022
Revenue
Brand revenue	$901	$940
Retail revenue	27,149	25,689
Total Revenue	$28,050	$26,629

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Year ended December 31,
	2023	2022
Brand revenue
United States	$889	$936
Canada	12	4
Retail revenue
United States	26,372	25,075
Canada	777	614
	$28,050	$26,629

Schedule Of Reverse Recapitalization [Line Items]

LEASES - Schedule of Lease Liabilities Mature (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
2024	$ 595	$ 124
2025	592	128
2026	504	110
2027		9
Total lease payments	4,403	371
Less imputed interest	(1,259)	(47)
Present value of lease liabilities	$ 3,144	$ 324	$ 781

FAIR VALUE MEASUREMENTS - Schedule Of Fair Value, Liabilities Measured on Recurring Basis (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Liabilities:
Derivative liability, noncurrent	$ 6	$ 3	$ 338
Total Fair Value	6	3	338
Public warrants
Liabilities:
Derivative liability, noncurrent	6	3
Level 1
Liabilities:
Total Fair Value	6	3	338
Level 1 \| Public warrants
Liabilities:
Derivative liability, noncurrent	6	3	338
Level 2
Liabilities:
Total Fair Value	0	0	0
Level 2 \| Public warrants
Liabilities:
Derivative liability, noncurrent	0	0	0
Level 3
Liabilities:
Total Fair Value	0	0	0
Level 3 \| Public warrants
Liabilities:
Derivative liability, noncurrent	$ 0	$ 0	$ 0

COMMITMENTS AND CONTINGENCIES (Q1)	3 Months Ended	12 Months Ended
COMMITMENTS AND CONTINGENCIES (Q1)	Mar. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE 16 – COMMITMENTS AND CONTINGENCIES Litigation The Company is from time to time involved in litigation incidental to the conduct of its business. In accordance with applicable accounting guidance, the Company records a provision for a liability when it is both probable that a liability has been incurred and the amount can be reasonably estimated. Management believes that the outcome of such legal proceedings, legal actions and claims will not have a significant adverse effect on the Company’s financial position, results of operations or cash flows. Employee Retention Payroll Tax Credits In March 2020, the U.S. government enacted the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) to provide economic and other relief as a result of the COVID-19 pandemic. The CARES Act includes, among other items, provisions relating to refundable employee retention payroll tax credits. Due to the complex nature of the employee retention credit computations, any benefits we may receive are uncertain and may significantly differ from our current estimates. We plan to record any benefit related to these credits upon both the receipt of the benefit and the resolution of the uncertainties, including, but not limited to, the completion of any potential audit or examination, or the expiration of the related statute of limitations. During the three months ended March 31, 2023, we received $2.0 million related to these credits, recognized $0.6 million as an offset related to operating expenses thorough accounts payable, and we have deferred recognition of remaining $1.4 million, which is recorded in current liabilities on the accompanying condensed consolidated balance sheets.	NOTE 16 – COMMITMENTS AND CONTINGENCIES Employment Agreements The Company has entered into employment agreements with Jeffrey Harris, CEO of SpringBig, and Paul Sykes, CFO of SpringBig, which became effective as of the consummation of the business combination. Litigation The Company evaluates the possible resolution of any legal and other contingencies when losses are possible in accordance with ASC 450, Contingencies (“ASC 450”). Significant judgment is required in both the determination of the probability of an outcome as well as the determination of an estimate of the amount of any potential loss. During the year ended December 31, 2023, the Company settled a dispute concerning the granting in 2017 of a non-exclusive, perpetual license to install and use certain of the Company’s software and derivative works, subject to certain limitations. As a result of the settlement, the Company recorded a liability of approximately $0.8 million. As of December 31, 2023, the Company has settled a portion of this liability through cash payments of $0.2 million and an equity issuance of $0.3 million. The remaining $0.3 million will be paid in equal installments of $40,000 on the last day of each month until the balance is settled in full by July 2024. The Company is from time to time involved in litigation incidental to the conduct of its business. In accordance with applicable accounting guidance, the Company records a provision for a liability when it is both probable that a liability has been incurred and the amount can be reasonably estimated. Management, after consulting legal counsel, believes that the outcome of such legal proceedings, legal actions and claims will not have a significant adverse effect on the Company’s financial position, results of operations or cash flows.

BUSINESS COMBINATIONS - Reverse Merger Narrative (FY) (Details) - USD ($)

1 Months Ended

3 Months Ended

12 Months Ended

Jun. 14, 2022

Feb. 28, 2022

Mar. 31, 2024

Mar. 31, 2023

Sep. 30, 2022

Dec. 31, 2023

Dec. 31, 2022

Apr. 29, 2022

Common stock, shares, outstanding (in shares)

25,290,270

45,594,864

26,940,841

45,339,762

26,659,711

Payment to redeeming stockholders

$ 191,437,817

Net proceeds from reverse recapitalization transaction

18,789,000

Gross proceeds available at closing

25,135,000

Proceeds from convertible notes

$ 7,000,000

$ 6,400,000

$ 0

$ 7,000,000

Amount available after paying TCAC redeeming stockholders

8,771,000

Proceeds from PIPE Financing

$ 6,100,000

Common stock issued for services rendered

$ 37,000

^[1]

$ 56,000

^[1]

$ 0

Stock Election Shareholders

Schedule Of Reverse Recapitalization [Line Items]

Common stock, shares, outstanding (in shares)

19,123,806

Stock redeemed during period, price per share (in dollars per share)

$ 10.01

TCAC non-redeeming shareholders

Schedule Of Reverse Recapitalization [Line Items]

Additional shares issued (in shares)

876,194

CF Principal Investments LLC

1,752,388

Schedule Of Reverse Recapitalization [Line Items]

Stock sale program, authorized amount

$ 50,000,000

Sale of stock, price per share (in dollars per share)

$ 0.0001

CF Principal Investments LLC | Affiliated Entity

Schedule Of Reverse Recapitalization [Line Items]

Common stock issued for services rendered

877,193

$ 1,500,000

PIPE Investors

Schedule Of Reverse Recapitalization [Line Items]

Convertible Notes Payable

1,341,356

Schedule Of Reverse Recapitalization [Line Items]

Proceeds from convertible notes

$ 10,000,000

Accrued interest payable, current

$ 305,000

15.00% Convertible Notes | Convertible Notes Payable

Schedule Of Reverse Recapitalization [Line Items]

730,493

Interest rate

15.00%

Repayments of debt

$ 7,000,000

[1]	Common shares issued in exchange for services rendered

ACCOUNTS RECEIVABLE (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

ACCOUNTS RECEIVABLE

NOTE 3 – ACCOUNTS RECEIVABLE

Accounts receivable, net consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Accounts receivable	$4,005	$3,690
Unbilled receivables	854	853
Total receivables	4,859	4,543
Less allowance for doubtful accounts	(1,648)	(1,595)
Accounts receivable, net	$3,211	$2,948

Bad debt expense was $87,000 and $169,000 for the three months ended March 31, 2024 and 2023, respectively, and is included in general and administrative expenses.

The following table details the activity related to the Company’s allowance for credit losses for the quarter ending March 31, 2024 (in thousands).

			Allowance for credit losses
Outstanding Balance, December 31, 2023			$1,595
Current-period provision (release) for expected credit losses			53
Write-offs charged against the allowance, net of recoveries and other			—
Outstanding Balance, March 31, 2024			$1,648

NOTE 3 – ACCOUNTS RECEIVABLE

Accounts receivable, net consisted of the following (in thousands):

	December 31,
	2023	2022
Accounts receivable	$3,690	$3,639
Unbilled receivables	853	731
Total receivables	4,543	4,370
Less allowance for credit losses	(1,595)	(1,481)
Accounts receivable, net	$2,948	$2,889

Bad debt expense was $1.6 million and $1.5 million for the years ending December 31, 2023 and 2022, respectively.

The following table details the activity related to the Company’s allowance for credit losses for the years ending December 31, 2023 and 2022, respectively (in thousands).

			Allowance for credit losses
Outstanding Balance, January 1, 2023			$1,481
Current-period provision (release) for expected credit losses			1,563
Write-offs charged against the allowance, net of recoveries and other			(1,449)
Outstanding Balance, December 31, 2023			$1,595

FAIR VALUE MEASUREMENTS - Changes in Fair Value (FY) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in fair value	$ 3,000	$ 153,000	$ (334,000)	$ (4,158,000)
Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3,000	$ 338,000	338,000	0
Assumed in business combination at fair value				4,496,000
Changes in fair value	3,000		(335,000)	(4,158,000)
Ending balance	$ 6,000		$ 3,000	$ 338,000

LEASES (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Supplemental Balance Sheet Information

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Balance Sheet
Assets:
Right of use asset - operating lease	$3,031	$340
Liabilities
Current	329	99
Non-current	2,815	225
Total operating lease liability	$3,144	$324

As of December 31, 2023, the following amounts were presented on SpringBig’s consolidated balance sheets in accordance with the Leasing Standard.

	Year ended December 31,
	2023	2022
Balance Sheet
Assets:
Right of Use Assets - Operating Lease	$340	$750
Liabilities:
Current	99	465
Non-current	225	316
Total Operating Lease Liabilities	$324	$781

Schedule of Lease Cost and Other Information

Other information pertaining to capitalized assets and liabilities under the leasing standard is as follows (in thousands):

	Three Months Ended March 31, 2024	Three Months Ended March 31, 2023
Other information
Operating lease cost	$160	$133
Operating cash flows paid to operating leases	$31	$126
Right-of-use assets in exchange for new operating lease liabilities	$2,781	$—
Weighted-average remaining lease term — operating leases (months)	89.9	17.9
Weighted-average discount rate — operating leases	9.05%	5.67%

Other information pertaining to capitalized assets and liabilities under the leasing standard is as follows.

	2023	2022
Other information
Operating lease cost	$486	$515
Operating cash flows from operating leases	$520	$318
Disposal of right-of-use assets	$299	$—
Disposal of operating lease liabilities associated with right-of-use assets	$313	$—
Right-of-use assets obtained in exchange for new operating lease liabilities	$412	$150
Weighted-average remaining lease term - operating leases (months)	35.1	20.4
Weighted-average discount rate - operating leases	9%	6%

Schedule of Lease Liability Maturity

As of March 31, 2024, the Company’s lease liabilities mature as follows:

Fiscal Year:			Operating Leases
2024			$434
2025			595
2026			592
2027			504
Thereafter			2,278
Total lease payments			4,403
Less Imputed Interest			(1,259)
Present value of lease liabilities			$3,144

As of December 31, 2023, the Company’s lease liabilities mature as follows:

			Operating Leases
Fiscal Year:
2024			$124
2025			128
2026			110
2027			9
Total lease payments			371
Less imputed interest			(47)
Present value of lease liabilities			$324

STOCKHOLDERS' EQUITY (Q1) (Details)	Jun. 14, 2022 day $ / shares shares	Mar. 31, 2024 $ / shares shares	Dec. 31, 2023 $ / shares shares	Dec. 31, 2022 $ / shares shares
Class of Stock [Line Items]
Sponsor earnout shares (in shares) \| shares	1,000,000
Stock price trigger (in dollars per share) \| $ / shares	$ 12
Number of trading days	20
Number of consecutive trading days	30
Capital stock authorized (in shares) \| shares	350,000,000
Common stock, shares authorized (in shares) \| shares	300,000,000	300,000,000	300,000,000	300,000,000
Preferred stock, shares authorized (in shares) \| shares	50,000,000
Common stock, par or stated value per share (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, par or stated value per share (in dollars per share) \| $ / shares	$ 0.0001
Contingent And Earnout Shares, Scenario One
Class of Stock [Line Items]
Contingent and earnout shares, to be issued (in shares) \| shares	7,000,000
Contingent and earnout shares, stock price threshold (usd per share) \| $ / shares	$ 12
Contingent and earnout shares, stock price threshold, triggering event period	20
Contingent and earnout shares, stock price threshold, trading days period	30
Contingent and earnout shares, stock price threshold, contingency period (in months)	60 months
Contingent And Earnout Shares, Scenario Two
Class of Stock [Line Items]
Contingent and earnout shares, to be issued (in shares) \| shares	2,250,000
Contingent and earnout shares, stock price threshold (usd per share) \| $ / shares	$ 15
Contingent and earnout shares, stock price threshold, triggering event period	20
Contingent and earnout shares, stock price threshold, trading days period	30
Contingent and earnout shares, stock price threshold, contingency period (in months)	60 months
Contingent And Earnout Shares, Scenario Three
Class of Stock [Line Items]
Contingent and earnout shares, to be issued (in shares) \| shares	1,250,000
Contingent and earnout shares, stock price threshold (usd per share) \| $ / shares	$ 18
Contingent and earnout shares, stock price threshold, triggering event period	20
Contingent and earnout shares, stock price threshold, trading days period	30
Contingent and earnout shares, stock price threshold, contingency period (in months)	60 months

STOCK BASED COMPENSATION - Schedule of Restricted Stock Units Outstanding (Q1) (Details) - Restricted Stock Units Outstanding - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Number of RSUs
Outstanding beginning balance (in shares)	2,211,509	725,000	0
RSUs granted (in shares)		1,989,000	761,500
RSUs forfeited (in shares	(50,000)	(276,836)	(36,500)
RSUs vested and common stock issued (in shares)		(225,655)
Outstanding ending balance (in shares)	2,161,509	2,211,509	725,000
Weighted Average Fair Value (Per Share)
Outstanding beginning balance (in dollars per share)	$ 0.8	$ 1.97
RSUs granted (in dollars per share)		0.56	$ 1.97
RSUs forfeited (in dollars per share)	0.8	1.28	1.97
RSUs vested and common stock issued (in dollars per share)		1.97
Outstanding ending balance (in dollars per share)	$ 0.79	$ 0.8	$ 1.97
Weighted Average Vesting (Years)	1 year 10 months 24 days	2 years 2 months 12 days	2 years 6 months

ACCRUED EXPENSES AND OTHER LIABILITIES (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Accrued wages, commission and bonus	$270	$393
Accrued professional fees	95	176
Deferred financial advisory fees	1,000	1,000
Other liabilities	402	382
	$1,767	$1,951

Accrued expenses and other current liabilities consisted of the following (in thousands):

	December 31,
	2023	2022
Accrued wages, commission and bonus	$393	$1,145
Accrued professional fees	176	148
Deferred financial advisory fees	1,000	1,000
Other liabilities	382	261
	$1,951	$2,554

CONSOLIDATED BALANCE SHEETS (Q1) (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 14, 2022
Statement of Financial Position [Abstract]
Common stock, par or stated value per share (in dollars per share)	$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	300,000,000	300,000,000		300,000,000	300,000,000
Common stock, shares, issued (in shares)	45,594,864	45,339,762	26,940,841	26,659,711	25,290,270
Common stock, shares, outstanding (in shares)	45,594,864	45,339,762	26,940,841	26,659,711	25,290,270

FAIR VALUE MEASUREMENTS - Schedule Of Fair Value, Liabilities Measured on Recurring Basis (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Liabilities:
Derivative liability, noncurrent	$ 6	$ 3	$ 338
Total Fair Value	6	3	338
Public warrants
Liabilities:
Derivative liability, noncurrent	6	3
Level 1
Liabilities:
Total Fair Value	6	3	338
Level 1 \| Public warrants
Liabilities:
Derivative liability, noncurrent	6	3	338
Level 2
Liabilities:
Total Fair Value	0	0	0
Level 2 \| Public warrants
Liabilities:
Derivative liability, noncurrent	0	0	0
Level 3
Liabilities:
Total Fair Value	0	0	0
Level 3 \| Public warrants
Liabilities:
Derivative liability, noncurrent	$ 0	$ 0	$ 0

WARRANT LIABILITIES (Q1) (Details) - USD ($)	3 Months Ended		12 Months Ended
WARRANT LIABILITIES (Q1) (Details) - USD ($)	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Jun. 14, 2022	Jun. 13, 2022
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative liability, noncurrent	$ 6,000		$ 3,000	$ 338,000
Change in fair value of warrants	(3,000)	$ (153,000)	334,000	4,158,000
Estimate of Fair Value Measurement
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative liability, noncurrent	$ 6,400		$ 3,200	$ 300,000
Redeemable Warrants \| Class A common stock
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Warrants outstanding (in shares)						10,000,000
Exercise price of warrants (in dollars per share)						$ 11.5
Warrants and rights outstanding					$ 6,000,000	$ 10,000,000
Number of shares issuable per each warrant (in shares)					1
Private Placement Warrant
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Warrants outstanding (in shares)					6,000,000
Exercise price of warrants (in dollars per share)						$ 11.5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Q1) (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Principles of Consolidation	The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.	The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Basis of Presentation	The financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).	The financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).
Foreign Currency	Foreign Currency We translate the condensed consolidated financial statements of our foreign subsidiaries, which have a functional currency in the respective country’s local currency, to U.S. dollars using month-end exchange rates for assets and liabilities and actual exchange rates for revenue, costs and expenses on the date of the transaction.	Foreign Currency We translate the financial statements of our foreign subsidiaries, which have a functional currency in the respective country’s local currency, to U.S. dollars using month-end exchange rates for assets and liabilities and actual exchange rates for revenue, costs and expenses on the date of the transaction. Translation gains and losses are included within “general and administrative expense” on the consolidated statements of operations. These gains and losses are immaterial to the financial statements.
Use of Estimates	Use of Estimates The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and revenues and expenses during the period reported. Certain accounting policies involve a “critical accounting estimate” because they are particularly dependent on estimates and assumptions made by management about matters that are highly uncertain at the time the accounting estimates are made. In addition, while we have used our best estimates based on facts and circumstances available to us at the time, different acceptable assumptions would yield different results. Changes in the accounting estimates are reasonably likely to occur from period to period, which may have a material impact on the presentation of our financial condition and results of operations. We review these estimates and assumptions periodically and reflect the effects of revisions in the period that they are determined to be necessary. We believe that the assumptions and estimates associated with income taxes, equity-based compensation (including issuance of common stock for services rendered), and allowance for credit losses have the greatest potential impact on our consolidated financial statements. Therefore, we consider the policies related to these financial areas to be our critical accounting policies. Future events and their effects cannot be predicted with certainty; accordingly, accounting estimates require the exercise of judgment. Accounting estimates used in the preparation of these financial statements change as new events occur, as more experience is acquired, as additional information is obtained, and as the operating environment changes. Actual results may differ materially from these estimates.	Use of Estimates The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and revenues and expenses during the period reported. Certain accounting policies involve a “critical accounting estimate” because they are particularly dependent on estimates and assumptions made by management about matters that are highly uncertain at the time the accounting estimates are made. In addition, while we have used our best estimates based on facts and circumstances available to us at the time, different acceptable assumptions would yield different results. Changes in the accounting estimates are reasonably likely to occur from period to period, which may have a material impact on the presentation of our financial condition and results of operations. We review these estimates and assumptions periodically and reflect the effects of revisions in the period that they are determined to be necessary. We believe that the assumptions and estimates associated with income taxes, equity-based compensation, and allowance for credit losses have the greatest potential impact on our consolidated financial statements. Therefore, we consider the policies related to income taxes, equity-based compensation, and allowance for credit losses to be our critical accounting policies. Future events and their effects cannot be predicted with certainty; accordingly, accounting estimates require the exercise of judgment. Accounting estimates used in the preparation of these financial statements change as new events occur, as more experience is acquired, as additional information is obtained, and as the operating environment changes. Actual results may differ materially from these estimates.
Segments	Segments The Company manages its business as a single operating segment. Our chief operating decision maker reviews financial information presented for the purposes of allocating resources and evaluating financial performance at an entity level and we have no segment managers who are held accountable by the chief operating decision maker for operations and operating results. The products and services across the Company are similar in nature, distributed in a comparable manner and have customers with common characteristics. We determined that we have one operating and reportable segment in accordance with Accounting Standards Codification (“ASC”) 280, Segment Reporting.	Segments The Company manages its business as a single operating segment. Our chief operating decision maker reviews financial information presented for the purposes of allocating resources and evaluating financial performance at an entity level and we have no segment managers who are held accountable by the chief operating decision maker for operations and operating results. The products and services across the company are similar in nature, distributed in a comparable manner and have customers with common characteristics. We determined that we have one operating and reportable segment in accordance with Accounting Standards Codification (“ASC”) 280, Segment Reporting.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Our financial assets, which include cash equivalents, current financial assets and our current financial liabilities have fair values that approximate their carrying value due to their short-term maturities.	Fair Value of Financial Instruments Our financial assets, which include cash equivalents, current financial assets and our current financial liabilities have fair values that approximate their carrying value due to their short-term maturities.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject us to concentration of credit risk consist principally of cash and cash equivalents and accounts receivable. We place our cash and cash equivalents with high credit-quality financial institutions. Such deposits may be in excess of federally insured limits. To date, we have not experienced any losses on our cash and cash equivalents. We perform periodic evaluations of the relative credit standing of the financial institutions. We perform ongoing credit evaluations of our customers’ financial condition and require no collateral from our customers. We maintain a credit loss reserve for expected credit losses based upon the expected collectability of accounts receivable balances. See Effective Accounting Pronouncements within this Note below for further information.	Concentrations of Credit Risk Financial instruments that potentially subject us to concentration of credit risk consist principally of cash and cash equivalents and accounts receivable. We place our cash and cash equivalents with high credit-quality financial institutions. Such deposits may be in excess of federally insured limits. We perform periodic evaluations of the relative credit standing of the financial institutions. We perform ongoing credit evaluations of our customers’ financial condition and require no collateral from our customers. We maintain an allowance for credit losses based upon the expected collectability of accounts receivable balances.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less, when acquired, to be cash equivalents. The Company maintains its cash with three commercial banks.	Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less, when acquired, to be cash equivalents. The Company maintains its cash with three commercial banks. As of December 31, 2023, the Company’s cash balances in interest and non-interest bearing deposit accounts were below the federally insured limits of $250,000 per financial institution. We monitor the financial condition of such institution and have not experienced any losses associated with these accounts.
Allowance for Credit Losses	Allowance for Credit Losses The Corporation's reserve methodology used to determine the appropriate level of the allowance for credit losses (“ACL”) is a critical accounting estimate. The ACL is maintained at a level believed to be appropriate to provide for the current credit losses expected to be incurred related to the Company’s accounts and unbilled receivables at the balance sheet date. The evaluation of expected losses is based on the probability of default using historical loss rates, as well as adjustments for forward-looking information, including industry and macroeconomic forecasts, as required. Management's current methodology includes utilizing a historical loss rate equivalent to the average loss rate during the preceding forty-eight months and applying this rate to accounts and unbilled receivables at the date of recording. This rate as well as the various quantitative and qualitative factors used in the methodologies are reviewed quarterly.	Allowance for Credit Losses The Corporation's reserve methodology used to determine the appropriate level of the allowance for credit losses (“ACL”) is a critical accounting estimate. The ACL is maintained at a level believed to be appropriate to provide for the current credit losses expected to be incurred related to the Company’s accounts and unbilled receivables at the balance sheet date. The evaluation of expected losses is based on the probability of default using historical loss rates, as well as adjustments for forward-looking information, including industry and macroeconomic forecasts, as required. Management's current methodology includes utilizing a historical loss rate equivalent to the average loss rate during the preceding forty-eight months and applying this rate to accounts and unbilled receivables at the date of recording. This rate as well as the various quantitative and qualitative factors used in the methodologies are reviewed quarterly.
Net Loss Per Share	Basic net income (loss) per share is computed by dividing the net income (loss) by the weighted-average number of shares of common stock outstanding during the period on a basic and diluted basis.	Earnings Per Share The Company computes net income per share in accordance with ASC 260, Earnings Per Share. Under the provisions of ASC 260, basic net income per share is computed by dividing the net income available to common shareholders by the weighted average common shares outstanding during the period. Diluted net income per share adjusts basic net income per share for the effects of stock options, warrants, convertible notes and restricted stock awards only in periods, or for such awards in which the effect is dilutive. ASC 260 also requires the Company to present basic and diluted earnings per share information separately for each class of equity instruments that participate in any income distribution with primary equity instruments.

6% SENIOR SECURED CONVERTIBLE NOTES (Q1) (Details)			1 Months Ended	3 Months Ended		12 Months Ended
6% SENIOR SECURED CONVERTIBLE NOTES (Q1) (Details)	Jan. 23, 2024 USD ($)	Jun. 14, 2022 USD ($)	Feb. 28, 2022 USD ($)	Mar. 31, 2024 USD ($) shares	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($)
Debt Instrument [Line Items]
Proceeds from issuance of convertible notes			$ 7,000,000	$ 6,400,000	$ 0	$ 0	$ 7,000,000
Purchase obligation	$ 2,900,000			2,895,000	1,457,000	3,238,000	1,000,000
Carrying value				8,000,000		0
Interest expense				875,000	391,000	$ 2,247,000	949,000
Gain on note repurchase				$ 1,573,000	0
Secured Convertible Notes
Debt Instrument [Line Items]
Warrants outstanding (in shares) \| shares				586,890		586,890
Warrants and rights outstanding				$ 839,000		$ 839,000
Maturity term (in years)		5 years
Secured Convertible Notes \| Measurement Input, Share Price
Debt Instrument [Line Items]
Convertible warrants, measurement input		4.28
Secured Convertible Notes \| Measurement Input, Conversion Price
Debt Instrument [Line Items]
Convertible warrants, measurement input		12
Secured Convertible Notes \| Measurement Input, Risk Free Interest Rate
Debt Instrument [Line Items]
Convertible warrants, measurement input		0.0361
Secured Convertible Notes \| Measurement Input, Price Volatility
Debt Instrument [Line Items]
Convertible warrants, measurement input		0.65
Convertible Notes Payable
Debt Instrument [Line Items]
Proceeds from issuance of convertible notes		$ 10,000,000
Senior Secured Original Issue Discount Convertible Note \| Convertible Notes Payable
Debt Instrument [Line Items]
Interest rate (as percent)		6.00%
Aggregate principal amount		$ 11,000,000
Discount issued on convertible notes		$ 1,000,000
Senior Secured Original Issue Discount Convertible Note \| Convertible Notes Payable
Debt Instrument [Line Items]
Interest rate (as percent)				6.00%
Discount issued on convertible notes						700,000	1,500,000
Carrying value				$ 0		5,100,000	9,800,000
Long-term debt, non-current						4,400,000	8,300,000
Interest expense				$ 14,000	$ 402,000	$ 402,000	$ 356,000

STOCKHOLDERS EQUITY - Conversions of Stock (FY) (Details)	Mar. 31, 2024 shares	Dec. 31, 2023 shares	Mar. 31, 2023 shares	Dec. 31, 2022 shares	Jun. 14, 2022 shares
Class of Stock [Line Items]
Common stock, shares, issued (in shares)	45,594,864	45,339,762	26,940,841	26,659,711	25,290,270
Common stock, shares, outstanding (in shares)	45,594,864	45,339,762	26,940,841	26,659,711	25,290,270
Recapitalization exchange ratio					0.59289
SpringBig
Class of Stock [Line Items]
Common stock, shares, issued (in shares)					8,362,933
Common stock, shares, outstanding (in shares)					8,362,933
Common and preferred stock, issued (in shares)					18,196,526
Common and preferred stock, outstanding (in shares)					18,196,526
Series B Preferred
Class of Stock [Line Items]
Recapitalization exchange ratio					0.59289
Series B Preferred \| SpringBig
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)					2,718,522
Preferred stock, shares outstanding (in shares)					2,718,522
Series A Preferred
Class of Stock [Line Items]
Recapitalization exchange ratio					0.59289
Series A Preferred \| SpringBig
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)					3,017,184
Preferred stock, shares outstanding (in shares)					3,017,184
Series Seed Preferred
Class of Stock [Line Items]
Recapitalization exchange ratio					0.59289
Series Seed Preferred \| SpringBig
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)					4,097,887
Preferred stock, shares outstanding (in shares)					4,097,887
SpringBig
Class of Stock [Line Items]
Common stock, shares, issued (in shares)					14,105,371
Common stock, shares, outstanding (in shares)					14,105,371
Common and preferred stock, issued (in shares)					30,691,232
Common and preferred stock, outstanding (in shares)					30,691,232
SpringBig \| Series B Preferred
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)					4,585,202
Preferred stock, shares outstanding (in shares)					4,585,202
SpringBig \| Series A Preferred
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)					5,088,944
Preferred stock, shares outstanding (in shares)					5,088,944
SpringBig \| Series Seed Preferred
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)					6,911,715
Preferred stock, shares outstanding (in shares)					6,911,715

FAIR VALUE MEASUREMENTS - Narrative (Q1) (Details)	Mar. 31, 2024 USD ($) $ / shares	Dec. 31, 2023 USD ($) $ / shares	Dec. 31, 2022 USD ($) $ / shares	Jun. 14, 2022 shares	Jun. 13, 2022 $ / shares shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, noncurrent \| $	$ 6,000	$ 3,000	$ 338,000
Measurement Input, Share Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability measurement input \| $ / shares	0.0004	0.0002	0.0211
Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, noncurrent \| $	$ 6,400	$ 3,200	$ 300,000
Redeemable Warrants \| Class A common stock
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants outstanding (in shares) \| shares					10,000,000
Exercise price of warrants (in dollars per share) \| $ / shares					$ 11.5
Number of shares issuable per each warrant (in shares) \| shares				1
Private Placement Warrant
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants outstanding (in shares) \| shares				6,000,000
Exercise price of warrants (in dollars per share) \| $ / shares					$ 11.5
Public warrants \| Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, noncurrent \| $	$ 6,400

ACCRUED EXPENSES AND OTHER LIABILITIES (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

ACCRUED EXPENSES AND OTHER LIABILITIES

NOTE 7 – ACCRUED EXPENSES AND OTHER LIABILITIES

Accrued expenses and other current liabilities consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Accrued wages, commission and bonus	$270	$393
Accrued professional fees	95	176
Deferred financial advisory fees	1,000	1,000
Other liabilities	402	382
	$1,767	$1,951

NOTE 7 – ACCRUED EXPENSES AND OTHER LIABILITIES

Accrued expenses and other current liabilities consisted of the following (in thousands):

	December 31,
	2023	2022
Accrued wages, commission and bonus	$393	$1,145
Accrued professional fees	176	148
Deferred financial advisory fees	1,000	1,000
Other liabilities	382	261
	$1,951	$2,554

PROPERTY AND EQUIPMENT (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

PROPERTY AND EQUIPMENT

NOTE 5 – PROPERTY AND EQUIPMENT

Property and equipment consist of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Computer equipment	$448	$416
Furniture & fixtures	176	149
Data warehouse	286	286
Software	197	197
Total cost	1,107	1,048
Less accumulated depreciation and amortization	(782)	(728)
Property and equipment, net	$325	$320

The useful life of computer equipment, software, furniture and fixtures, and the data warehouse is three years.

Depreciation and amortization expense for the three months ended March 31, 2024 and 2023 was $54,000 and $66,000, respectively. The amounts are included in general and administrative expenses in the condensed consolidated statements of operations.

NOTE 5 – PROPERTY AND EQUIPMENT

Property and equipment consist of the following (in thousands):

	December 31,
	2023	2022
Computer equipment	$416	$333
Furniture and fixtures	149	15
Data warehouse	286	286
Software	197	197
Total Cost	1,048	831
Less accumulated depreciation and amortization	(728)	(456)
Property and Equipment	$320	$375

The useful life of computer equipment, furniture and fixtures, software and the data warehouse is 3 years.

Depreciation and amortization expenses for the years ended December 31, 2023 and 2022 were $272,000 and $259,000, respectively. The amounts are included in general and administrative expenses in the consolidated statements of operations.

NET INCOME (LOSS) PER SHARE - Narrative (Q1) (Details) - shares	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 14, 2022
Earnings Per Share [Abstract]
Common stock, shares, issued (in shares)	45,594,864	45,339,762	26,940,841	26,659,711	25,290,270
Common stock, shares, outstanding (in shares)	45,594,864	45,339,762	26,940,841	26,659,711	25,290,270

DESCRIPTION OF BUSINESS (FY)	3 Months Ended	12 Months Ended
DESCRIPTION OF BUSINESS (FY)	Mar. 31, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS	NOTE 1 – DESCRIPTION OF BUSINESS SpringBig Holdings, Inc. and its wholly-owned subsidiaries (the “Company,” “we,” “us,”, “our”, or “SpringBig”) developed a software platform that provides marketing and customer engagement services to cannabis dispensaries and brands throughout the United States and Canada. The Company allows merchants to provide loyalty plans and rewards directly to consumers through an internet portal and mobile applications. Our operational headquarters are in Boca Raton, Florida, with additional offices located in the United States and Canada. The Company has one direct wholly-owned subsidiary, SpringBig, Inc. On June 14, 2022 (the “Closing Date”), SpringBig Holdings, Inc. (formerly known as Tuatara Capital Acquisition Corporation (“Tuatara” or “TCAC”)), consummated the business combination of SpringBig, Inc. (“Legacy SpringBig”) and HighJump Merger Sub, Inc., the wholly-owned subsidiary of Tuatara, pursuant to the Amended and Restated Agreement of Plan Merger, dated as of April 14, 2022, as amended, by and among Tuatara, HighJump Merger Sub, Inc. and Legacy SpringBig. Prior to the closing of the business combination (the “Closing”), Tuatara changed its jurisdiction of incorporation by deregistering as a Cayman Islands exempted company and continuing and domesticating as a corporation incorporated under the laws of the State of Delaware. In connection with the Closing, the registrant changed its name from Tuatara Capital Acquisition Corporation to “SpringBig Holdings, Inc.” SpringBig will continue the existing business operations of Legacy SpringBig as a publicly traded company. Beginning June 15, 2022, the ticker symbols for the Company’s common stock and publicly traded warrants were changed to “SBIG” and “SBIGW,” respectively, and commenced trading on The Nasdaq Capital Market. On September 1, 2023, the Board of Directors of SpringBig Holdings, Inc. determined that it would not be in the best interest of the Company or its shareholders to meet the continued listing requirements of the Nasdaq Capital Market, and the Company notified the Nasdaq Stock Market LLC (“Nasdaq”) that it was withdrawing its appeal of the Nasdaq Listings Qualification staff’s delist determination dated March 7, 2023, for the Company’s failure to meet the market value of listed securities requirement in the Nasdaq Listing Rules. The Company’s common stock is now quoted for trading on the OTCQX® Best Market and its public warrants are now quoted for trading on the OTC Pink Market under their current trading symbols “SBIG” and “SBIGW,” respectively. The Company’s common stock started trading on the OTCQX® Best Market on September 6, 2023. The Company remains a reporting company under the Securities Exchange Act of 1934, as amended (the “Exchange Act”).	NOTE 1 – DESCRIPTION OF BUSINESS SpringBig Holdings, Inc. and its wholly-owned subsidiaries (the “Company,” “we,” “us,”, “our”, or “SpringBig”) developed a software platform that provides marketing and customer engagement services to cannabis dispensaries and brands throughout the United States and Canada. The Company allows merchants to provide loyalty plans and rewards directly to consumers through an internet portal and mobile applications. Our operational headquarters are in Boca Raton, Florida, with additional offices located in the United States and Canada. The Company has one direct wholly-owned subsidiary, SpringBig, Inc. On June 14, 2022 (the “Closing Date”), SpringBig Holdings, Inc. (formerly known as Tuatara Capital Acquisition Corporation (“Tuatara” or “TCAC”)), consummated the business combination of SpringBig, Inc. (“Legacy SpringBig”) and HighJump Merger Sub, Inc., the wholly-owned subsidiary of Tuatara, pursuant to the Amended and Restated Agreement of Plan Merger, dated as of April 14, 2022, as amended, by and among Tuatara, HighJump Merger Sub, Inc. and Legacy SpringBig. Prior to the closing of the business combination (the “Closing”), Tuatara changed its jurisdiction of incorporation by deregistering as a Cayman Islands exempted company and continuing and domesticating as a corporation incorporated under the laws of the State of Delaware. In connection with the Closing, the registrant changed its name from Tuatara Capital Acquisition Corporation to “SpringBig Holdings, Inc.” SpringBig will continue the existing business operations of Legacy SpringBig as a publicly traded company. See Note 9, Business Combinations, to these consolidated financial statements for further information. While the legal acquirer in the business combination is SpringBig for financial accounting and reporting purposes under U.S. GAAP, Legacy SpringBig is the accounting acquirer, with the merger accounted for as a “reverse recapitalization.” A reverse recapitalization does not result in a new basis of accounting, and the financial statements of the combined entity represent the continuation of the financial statements of Legacy SpringBig. Under this accounting method, SpringBig is treated as the “acquired” company and Legacy SpringBig is the accounting acquirer, with the transaction treated as a recapitalization of Legacy SpringBig. SpringBig’s assets, liabilities and results of operations were consolidated with Legacy SpringBig’s beginning on the date of the business combination. Except for certain warrant liabilities, the assets and liabilities of SpringBig were recognized at historical cost (which is consistent with carrying value) and were not material, with no goodwill or other intangible assets recorded. The warrant liabilities, which are discussed in Note 12, Warrant Liabilities, were recorded at fair value. The consolidated assets, liabilities, and results of operations of Legacy SpringBig became the historical financial statements, and operations prior to the closing of the business combination presented for comparative purposes are those of Legacy SpringBig. Pre-merger shares of common stock and preferred stock of Legacy SpringBig were converted to shares of common stock of the combined company using the conversion ratio of 0.59289 and for comparative purposes, the shares and net loss per share of Legacy SpringBig prior to the merger have been retroactively restated using the conversion ratio. Beginning June 15, 2022, the ticker symbols for the Company’s common stock and publicly-traded warrants were changed to “SBIG” and “SBIGW,” respectively, and commenced trading on The Nasdaq Capital Market. The Company received net proceeds of $18.8 million, with gross proceeds of $25.1 million, which were in addition to the $7.0 million in Convertible Notes proceeds, which were received in February 2022 in connection with Legacy SpringBig’s issuance of such notes (and which Convertible Notes and the interest due thereon were converted into common stock in connection with the business combination. See Note 10, 15% Convertible Promissory Notes, to these consolidated financial statements). Of the amount received at the Closing, approximately $8.8 million represented cash from the TCAC trust related to unredeemed shares; $6.1 million represented proceeds from the subscription for common stock from certain investors (the “PIPE Financing”), and $10.0 million from the Secured Convertible Note (defined below). The Company incurred additional cash and non cash expenses totaling $8.7 million, resulting in net business combination proceeds of $10.1 million. On September 1, 2023, (i) the Board of Directors of SpringBig Holdings, Inc. determined that it would not be in the best interest of the Company or its shareholders to meet the continued listing requirements of the Nasdaq Capital Market, (ii) the Company notified the Nasdaq Stock Market LLC (“Nasdaq”) that it was withdrawing its appeal of the Nasdaq Listings Qualification staff’s delist determination dated March 7, 2023, for the Company’s failure to meet the market value of listed securities requirement in Nasdaq Listing Rule 5450(b)(2)(A) and (iii) the Company received a letter from Nasdaq confirming (a) the withdrawal of the appeal, (b) as a result of the withdrawal, the Company’s common stock and public warrants would be suspended at the open of business on September 5, 2023 and (c) Nasdaq would file a Form 25 Notification of Delisting with the SEC when all of its internal procedural periods have run. The letter also noted that the Company failed to meet the minimum bid price requirement in Nasdaq Listing Rule 5450(a)(1). The Company’s common stock is now quoted for trading on the OTCQX® Best Market and its public warrants are now quoted for trading on the OTC Pink Market under their current trading symbols “SBIG” and “SBIGW,” respectively, following the delisting from trading on the Nasdaq Capital Market. The Company’s common stock started trading on the OTCQX® Best Market on September 6, 2023. The Company remains a reporting company under the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

LEASES (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

LEASES

NOTE 15 – LEASES

The Company leases office facilities in Boca Raton, Florida, Seattle, Washington and Ontario, Canada under non-cancelable operating lease agreements. The leases require monthly payments ranging from $4,000 to $48,000 and expire on various dates through February 2032. In addition to minimum rent, the Company is required to pay a proportionate share of operating expenses under these leases.

In June 2022, the Company entered into a new lease which became effective on January 1, 2024 after completion of leasehold improvements. The new lease term is for 98 months and monthly rental payments range from $38,000 to $48,000 over the life of the lease.

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Balance Sheet
Assets:
Right of use asset - operating lease	$3,031	$340
Liabilities
Current	329	99
Non-current	2,815	225
Total operating lease liability	$3,144	$324

For the three months ended March 31, 2024 and March 31, 2023, the Company’s operating lease cost was $160,000 and $133,000, respectively. Other information pertaining to capitalized assets and liabilities under the leasing standard is as follows (in thousands):

	Three Months Ended March 31, 2024	Three Months Ended March 31, 2023
Other information
Operating lease cost	$160	$133
Operating cash flows paid to operating leases	$31	$126
Right-of-use assets in exchange for new operating lease liabilities	$2,781	$—
Weighted-average remaining lease term — operating leases (months)	89.9	17.9
Weighted-average discount rate — operating leases	9.05%	5.67%

As of March 31, 2024, the Company’s lease liabilities mature as follows:

Fiscal Year:			Operating Leases
2024			$434
2025			595
2026			592
2027			504
Thereafter			2,278
Total lease payments			4,403
Less Imputed Interest			(1,259)
Present value of lease liabilities			$3,144

NOTE 17 – LEASES

As discussed in Note 2, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) in February 2016 (“Lease Standard”). The amendments are effective for fiscal years beginning after December 15, 2021, for all entities, and interim periods within those fiscal years for public business entities and interim periods within fiscal years beginning after December 15, 2022, for all other entities. The Company adopted this standard on January 1, 2022.

SpringBig elected to take the cumulative transition approach to accounting for the adoption of the Lease Standard. This approach requires entities to apply the ASC 842 requirements in the period of adoption (i.e., assuming an adoption date of January 1, 2022, SpringBig’s comparative financial statements for the years ended December 31, 2022 and 2021 would need to apply ASC 842 only for the year ended December 31, 2022). As of the adoption date of January 1, 2022, the Company recorded ROU assets of $1.1 million and lease liabilities of $1.1 million. A cumulative effect adjustment to equity of $31,000 was recorded as of the adoption date.

The Company leases office facilities in Boca Raton, Florida, Seattle, Washington and Ontario, Canada under non-cancelable operating lease agreements. The leases require monthly payments ranging from $4,000 to $7,000 and expire on various dates through February 2027. In addition to minimum rent, the Company is required to pay a proportionate share of operating expenses under these leases.

In June of 2022, the Company entered into a lease with the current landlord for the Company’s corporate headquarters under which the current leases will be replaced by the new lease on a single floor in the same building as the Company currently occupies. The new lease commenced during January 2024. The new lease term is for 98 months. Monthly rental payments range from $38,000 to $48,000 over the life of the lease. As of December 31, 2023, the Company’s existing leases were terminated and the associated right of use assets and operating lease liabilities were written off, resulting in an $14,000 gain for the year ended December 31, 2023. The resultant gain is included in general and administrative expenses on the Company’s consolidated statements of operations.

Lease expense was approximately $725,000 and $846,000 for the years ended December 31, 2023 and 2022, respectively, which is recorded in general and administrative expenses on the consolidated statement of operations. Of the $725,000 and $846,000 for the years ended December 31, 2023 and 2022, respectively, $486,000 and $515,000 related to operating leases under ASC 842 with the remainder attributable to common area maintenance, taxes, and other charges, respectively.

As of December 31, 2023, the following amounts were presented on SpringBig’s consolidated balance sheets in accordance with the Leasing Standard.

	Year ended December 31,
	2023	2022
Balance Sheet
Assets:
Right of Use Assets - Operating Lease	$340	$750
Liabilities:
Current	99	465
Non-current	225	316
Total Operating Lease Liabilities	$324	$781

For both years ending December 31, 2023 and 2022, the Company’s operating lease cost was $0.5 million and is recorded in general and administrative expenses on the Company’s consolidated statements of operations. Other information pertaining to capitalized assets and liabilities under the leasing standard is as follows.

	2023	2022
Other information
Operating lease cost	$486	$515
Operating cash flows from operating leases	$520	$318
Disposal of right-of-use assets	$299	$—
Disposal of operating lease liabilities associated with right-of-use assets	$313	$—
Right-of-use assets obtained in exchange for new operating lease liabilities	$412	$150
Weighted-average remaining lease term - operating leases (months)	35.1	20.4
Weighted-average discount rate - operating leases	9%	6%

As of December 31, 2023, the Company’s lease liabilities mature as follows:

			Operating Leases
Fiscal Year:
2024			$124
2025			128
2026			110
2027			9
Total lease payments			371
Less imputed interest			(47)
Present value of lease liabilities			$324

RELATED PARTY TRANSACTIONS (Q1)	3 Months Ended	12 Months Ended
RELATED PARTY TRANSACTIONS (Q1)	Mar. 31, 2024	Dec. 31, 2023
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	NOTE 8 – RELATED PARTY TRANSACTIONS The Company incurred software development and information technology related costs to a vendor related through common ownership to a major stockholder of approximately $2,000 for the three months ended March 31, 2024, and $4,000 for the three months ended March 31, 2023, respectively, and the related expense is recorded to technology and software development costs on the condensed consolidated statement of operations. Amounts due to this related party were $2,000 and $2,000 at March 31, 2024 and December 31, 2023, respectively. The $540,000 related party payable at December 31, 2023, was repaid in January 2024, following completion of the issuance of $6.4 million aggregate principal amount of 8% Secured Convertible Notes and $1.6 million aggregate principal amount of 12% Secured Term Notes. Jeffrey Harris, CEO, and Paul Sykes, CFO, both participated in the debt financing transaction completed on January 23, 2024. Jeffrey Harris purchased $320,000 8% Secured Convertible Notes, due 2026, and $80,000 12% Secured Term Notes, due 2026. Paul Sykes purchased $25,000 8% Secured Convertible Notes, due 2026, and $6,250 12% Secured Term Notes, due 2026. There are two members of the board of directors at March 31, 2024, who are related parties to investors in the debt financing transaction completed on January 23, 2024. In aggregate these investors purchased $5.2 million 12% Secured Convertible Notes and $1.3 million 8% Secured Term Notes.	NOTE 8 – RELATED PARTY TRANSACTIONS The Company incurred software development and information technology related costs to a vendor related through common ownership to a major stockholder of approximately $13,000 and $153,000 for the years ended December 31, 2023 and 2022, respectively. These amounts are included in technology and software development expenses. At December 31, 2023 and 2022, the Company has recorded $2,000 and $3,000, respectively, in accounts payable related to this related party vendor. During 2023, SpringBig’s CEO, Jeffrey Harris, advanced and paid certain expenses on behalf of the Company of approximately $1.0 million for use in operations. As of December 31, 2023, the Company repaid Mr. Harris approximately $0.5 million. The remaining $0.5 million is included in current liabilities on the Company’s consolidated balance sheets.

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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15% CONVERTIBLE PROMISSORY NOTES (FY) (Details) - USD ($)		1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 14, 2022	Feb. 28, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Short-Term Debt [Line Items]
Interest expense			$ 875,000	$ 391,000	$ 2,247,000	$ 949,000
Convertible Notes Payable
Short-Term Debt [Line Items]
Accrued interest payable, current	$ 305,000
15.00% Convertible Notes \| Convertible Notes Payable
Short-Term Debt [Line Items]
Interest rate	15.00%	15.00%
Aggregate principal amount		$ 7,000,000
Issue of common stock (in shares)	730,493	730,493
Share price (in dollars per share)		$ 10
Interest expense						$ 305,000

STOCK BASED COMPENSATION - Stock Options Outstanding (FY) (Details)	3 Months Ended	5 Months Ended	7 Months Ended	12 Months Ended
	Mar. 31, 2024 $ / shares shares	Jun. 14, 2022 $ / shares shares	Dec. 31, 2022 $ / shares shares	Dec. 31, 2023 $ / shares shares	Dec. 31, 2022 $ / shares shares	Dec. 31, 2021 $ / shares shares
Number of Options
Outstanding beginning balance (in shares) \| shares	2,271,894		3,679,171	3,394,753
Options exercised (in shares) \| shares	0		(135,090)	(727,233)
Options forfeited (in shares) \| shares	(2,964)		(149,328)	(25,876)
Options cancelled (in shares) \| shares	0			(369,750)
Outstanding ending balance (in shares) \| shares	2,268,930	3,679,171	3,394,753	2,271,894	3,394,753
Weighted Average Exercise Price (Per Share)
Outstanding beginning balance (in dollars per share) \| $ / shares	$ 0.57			$ 0.57
Options exercised (in dollars per share) \| $ / shares	0		$ 0.3	0.38
Options forfeited (in dollars per share) \| $ / shares	1.26		1.11	0.82
Options cancelled (in dollars per share) \| $ / shares	0			0.84
Outstanding ending balance (in dollars per share) \| $ / shares	$ 0.57		$ 0.57	$ 0.57	$ 0.57
Number of Options (in shares) \| shares	2,255,034		3,250,236	2,244,102	3,250,236
Options Vested and Exercisable, Weighted Average Remaining Contractual Life (Years)	4 years 6 months 25 days			4 years 9 months 3 days	5 years 9 months 14 days
Options Vested and Exercisable, Weighted Average Exercise Price (in dollars per share) \| $ / shares	$ 0.57		$ 0.54	$ 0.56	$ 0.54
SpringBig
Number of Options
Outstanding beginning balance (in shares) \| shares		6,802,437	6,205,520		6,802,437
Options exercised (in shares) \| shares		(530,666)
Options forfeited (in shares) \| shares		(61,460)
Options cancelled (in shares) \| shares		(4,791)
Outstanding ending balance (in shares) \| shares		6,205,520				6,802,437
Conversion ratio (in shares)		0.5929
Weighted Average Exercise Price (Per Share)
Outstanding beginning balance (in dollars per share) \| $ / shares		$ 0.38			$ 0.38
Options exercised (in dollars per share) \| $ / shares		0.55
Options forfeited (in dollars per share) \| $ / shares		0.75
Options cancelled (in dollars per share) \| $ / shares		$ 0.75
Outstanding ending balance (in dollars per share) \| $ / shares						$ 0.38
Number of Options (in shares) \| shares						4,628,311
Options Vested and Exercisable, Weighted Average Remaining Contractual Life (Years)						6 years 9 months 14 days
Options Vested and Exercisable, Weighted Average Exercise Price (in dollars per share) \| $ / shares						$ 0.24

CONVERTIBLE NOTE RECEIVABLE (Q1)	3 Months Ended	12 Months Ended
CONVERTIBLE NOTE RECEIVABLE (Q1)	Mar. 31, 2024	Dec. 31, 2023
Receivables [Abstract]
CONVERTIBLE NOTE RECEIVABLE	NOTE 6 – CONVERTIBLE NOTE RECEIVABLE In April 2022, the Company purchased $250,000 in aggregate principal amount of convertible promissory note due April 1, 2026 (the “Convertible Note Receivable”). The Convertible Note Receivable accrued interest at the rate of 5% per annum on the principal amount of the Convertible Note Receivable. The Company determined that the fair value of the Convertible Note was $0 at December 31, 2023. The loss of $272,000, including $22,000 of accrued interest income, was recorded in interest expense on the Company’s condensed consolidated statements of operations for the year ended December 31, 2023.	NOTE 6 – CONVERTIBLE NOTE RECEIVABLE In April 2022, the Company purchased $250,000 in aggregate principal amount of convertible promissory note due April 1, 2026 (the “Convertible Note Receivable”). The Convertible Note Receivable accrued interest at the rate of 5% per annum on the principal amount of the Convertible Note Receivable. The Company determined that the fair value of the Convertible Note was $0 at December 31, 2023. The loss of $272,000, including $22,000 of accrued interest income, was recorded in general and administrative expenses on the Company’s consolidated statements of operations.

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (Q1) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net income (loss)	$ 417,000	$ (2,262,000)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Gain on note repurchase	(1,573,000)	0
Non-cash interest expense	108,000	0
Depreciation and amortization	54,000	66,000
Discount amortization on convertible note	0	259,000
Amortization of debt financing costs	116,000	0
Stock-based compensation	195,000	162,000
Bad debt expense	87,000	169,000
Accrued interest on convertible notes	117,000	22,000
Amortization of operating lease right of use assets	90,000	123,000
Change in fair value of warrants	3,000	153,000
Changes in operating assets and liabilities:
Accounts receivable	(351,000)	(448,000)
Prepaid expenses and other current assets	305,000	474,000
Contract assets	18,000	10,000
Accounts payable and other liabilities	(1,505,000)	363,000
Deferred payroll tax credits	0	1,442,000
Operating lease liabilities	39,000	(126,000)
Deferred revenue	2,000	(28,000)
Net cash provided by (used in) operating activities	(1,878,000)	379,000
Cash flows from investing activities:
Purchase of convertible note	0	(3,000)
Purchases of property and equipment	(59,000)	(9,000)
Net cash used in investing activities	(59,000)	(12,000)
Cash flows from financing activities:
Proceeds from issuance of convertible notes	6,400,000	0
Repayment of convertible notes	(2,895,000)	(1,457,000)
Proceeds from issuance of term notes	1,600,000	0
Repayment of short-term cash advance	(730,000)	0
Repayment of related party payable	(540,000)	0
Cost of convertible and term note issuance	(561,000)	0
Proceeds from exercise of stock options	0	113,000
Net cash provided by (used in) financing activities	3,274,000	(1,344,000)
Net increase (decrease) in cash and cash equivalents	1,337,000	(977,000)
Cash and cash equivalents at beginning of period	331,000	3,546,000
Cash and cash equivalents at end of period	1,668,000	2,569,000
Supplemental cash flows disclosures
Interest paid	589,000	132,000
Common stock issued for services rendered relating to debt financing	37,000	0
Accrued cost of debt issuance	319,000	0
Obtaining a right-of-use asset in exchange for a lease liability	$ 2,781,000	$ 0

FAIR VALUE MEASUREMENTS (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

FAIR VALUE MEASUREMENTS

NOTE 17 – FAIR VALUE MEASUREMENTS

The following fair value hierarchy is used to classify assets and liabilities based on the observable inputs and unobservable inputs used in order to value the assets and liabilities:

Liabilities measured at fair value on a recurring basis

The balances of the Company’s liabilities measured at fair value on a recurring basis as of March 31, 2024, are as follows (in thousands):

	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	6	—	—	6
	$6	$—	$—	$6

The balances of the Company’s liabilities measured at fair value on a recurring basis as of December 31, 2023, are as follows (in thousands):

	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	3	—	—	3
	$3	$—	$—	$3

The following is a description of the methodologies used to estimate the fair values of liabilities measured at fair value on a recurring basis and within the fair value hierarchy.

Warrant liabilities

At March 31, 2024, the value of the public warrants was approximately $6,400 using a closing price of $0.0004.

Changes in Fair Value

The following tables provides a roll-forward in the changes in fair value in the public warrants for the three months ended March 31, 2024 (in thousands):

Warrants
Balance, January 1, 2024			$3
Change in fair value			3
Balance, March 31, 2024			$6
Changes in fair value included in earnings for the period relating to liabilities held at March 31, 2024			$3

There were no transfers of financial liabilities between levels of the fair value hierarchy during the three months ended March 31, 2024.

NOTE 18 – FAIR VALUE MEASUREMENTS

The following fair value hierarchy is used to classify assets and liabilities based on the observable inputs and unobservable inputs used in order to value the assets and liabilities:

Liabilities measured at fair value on a recurring basis

The balances of the Company’s liabilities measured at fair value on a recurring basis as of December 31, 2023 and 2022, are as follows (in thousands):

For the year ended December 31, 2022	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	338	—	—	338
	$338	$—	$—	$338

For the year ended December 31, 2023	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	3	—	—	3
	$3	$—	$—	$3

The following is a description of the methodologies used to estimate the fair values of liabilities measured at fair value on a recurring basis and within the fair value hierarchy.

Warrant liabilities

Changes in Fair Value

Warrants
Balance, January 1, 2022			$—
Assumed in business combination at fair value			$4,496
Change in value			$(4,158)
Balance, December 31, 2022			$338
Changes in fair value included in earnings for the period relating to liabilities held at December 31, 2022			$(4,158)

Balance, January 1, 2023			$338
Change in fair value			(335)
Balance, December 31, 2023			$3
Changes in fair value included in earnings for the period relating to liabilities held at December 31, 2023			$(335)

There were no transfers of financial liabilities between levels of the fair value hierarchy during the year ended December 31, 2023.

WARRANT LIABILITIES (FY) (Details) - USD ($)	3 Months Ended		12 Months Ended
WARRANT LIABILITIES (FY) (Details) - USD ($)	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Jun. 14, 2022	Jun. 13, 2022
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Warrant liabilities	$ 6,000		$ 3,000	$ 338,000
Change in fair value of warrants	(3,000)	$ (153,000)	334,000	4,158,000
Estimate of Fair Value Measurement
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Warrant liabilities	$ 6,400		$ 3,200	$ 300,000
Redeemable Warrants \| Class A common stock
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Warrants outstanding (in shares)						10,000,000
Exercise price of warrants (in dollars per share)						$ 11.5
Warrants and rights outstanding					$ 6,000,000	$ 10,000,000
Number of shares issuable per each warrant (in shares)					1
Private Placement Warrant
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Warrants outstanding (in shares)					6,000,000
Exercise price of warrants (in dollars per share)						$ 11.5

PROPERTY AND EQUIPMENT (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Property and Equipment

Property and equipment consist of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Computer equipment	$448	$416
Furniture & fixtures	176	149
Data warehouse	286	286
Software	197	197
Total cost	1,107	1,048
Less accumulated depreciation and amortization	(782)	(728)
Property and equipment, net	$325	$320

Property and equipment consist of the following (in thousands):

	December 31,
	2023	2022
Computer equipment	$416	$333
Furniture and fixtures	149	15
Data warehouse	286	286
Software	197	197
Total Cost	1,048	831
Less accumulated depreciation and amortization	(728)	(456)
Property and Equipment	$320	$375

ACCRUED EXPENSES AND OTHER LIABILITIES (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Accrued wages, commission and bonus	$270	$393
Accrued professional fees	95	176
Deferred financial advisory fees	1,000	1,000
Other liabilities	402	382
	$1,767	$1,951

Accrued expenses and other current liabilities consisted of the following (in thousands):

	December 31,
	2023	2022
Accrued wages, commission and bonus	$393	$1,145
Accrued professional fees	176	148
Deferred financial advisory fees	1,000	1,000
Other liabilities	382	261
	$1,951	$2,554

REVENUE RECOGNITION (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Disaggregation of Revenue

The following table represents our revenues disaggregated by type (in thousands):

	Three Months Ended March 31,
	2024	2023
Revenue
Brand revenue	$59	$295
Retail revenue	6,415	6,862
Total revenue	$6,474	$7,157

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Three Months Ended March 31,
	2024	2023
Brand revenue
United States	$59	$294
Canada	—	1
Retail revenue
United States	6,273	6,663
Canada	142	199
	$6,474	$7,157

The following table represents our revenues disaggregated by type (in thousands):

	Year ended December 31,
	2023	2022
Revenue
Brand revenue	$901	$940
Retail revenue	27,149	25,689
Total Revenue	$28,050	$26,629

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Year ended December 31,
	2023	2022
Brand revenue
United States	$889	$936
Canada	12	4
Retail revenue
United States	26,372	25,075
Canada	777	614
	$28,050	$26,629

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Q1) (Details) $ in Thousands		3 Months Ended		12 Months Ended
	Jan. 23, 2024 USD ($)	Mar. 31, 2024 USD ($) segment	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)
Concentration Risk [Line Items]
Accumulated deficit		$ 36,148		$ 36,565	$ 26,332
Cash flows used in operating activities		1,878	$ (379)	3,976	14,518
Working capital		(1,400)		(9,100)
Cash and cash equivalents		$ 1,668		$ 331	$ 3,546
Number of operating segments \| segment		1		1
Number of reportable segments \| segment		1		1
Cash in excess of insured limits		$ 1,300
8% Secured Convertible Notes, due January 23, 2026 \| Convertible Debt
Concentration Risk [Line Items]
Aggregate principal amount	$ 6,400
Interest rate (as percent)	8.00%
Debt instrument, term (in years)	2 years
12% Secured Term Notes, due January 23, 2026 \| Secured Debt
Concentration Risk [Line Items]
Aggregate principal amount	$ 1,600
Interest rate (as percent)	12.00%
Debt instrument, term (in years)	2 years
Senior Secured Original Issue Discount Convertible Note \| Convertible Notes Payable
Concentration Risk [Line Items]
Interest rate (as percent)		6.00%
Revenue from Contract with Customer Benchmark \| One Customer \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage		14.00%	12.00%	14.00%	11.00%
Accounts Receivable \| One Customer \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage					12.00%
Accounts Receivable \| Two Customers \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage		23.00%		30.00%
Cost of Goods and Service Benchmark \| Supplier Concentration Risk \| One Vendor
Concentration Risk [Line Items]
Concentration risk, percentage		60.00%	75.00%	86.00%
Cost of Goods and Service Benchmark \| Supplier Concentration Risk \| Two Vendor
Concentration Risk [Line Items]
Concentration risk, percentage					86.00%
Accounts Payable \| Supplier Concentration Risk \| One Vendor
Concentration Risk [Line Items]
Concentration risk, percentage		26.00%
Accounts Payable \| Supplier Concentration Risk \| Two Vendor
Concentration Risk [Line Items]
Concentration risk, percentage			30.00%	30.00%

REVENUE RECOGNITION - Schedule of Disaggregation of Revenue (Q1) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Total revenue	$ 6,474	$ 7,157	$ 28,050	$ 26,629
Brand revenue
Disaggregation of Revenue [Line Items]
Total revenue	59	295	901	940
Brand revenue \| United States
Disaggregation of Revenue [Line Items]
Total revenue	59	294	889	936
Brand revenue \| Canada
Disaggregation of Revenue [Line Items]
Total revenue	0	1	12	4
Retail revenue
Disaggregation of Revenue [Line Items]
Total revenue	6,415	6,862	27,149	25,689
Retail revenue \| United States
Disaggregation of Revenue [Line Items]
Total revenue	6,273	6,663	26,372	25,075
Retail revenue \| Canada
Disaggregation of Revenue [Line Items]
Total revenue	$ 142	$ 199	$ 777	$ 614

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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LEASES - Schedule of Lease Cost and Other Information (FY) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease cost	$ 160,000	$ 133,000	$ 486,000	$ 515,000
Operating cash flows from operating leases	31,000	126,000	520,000	318,000
Disposal of right-of-use assets			299,000	0
Disposal of operating lease liabilities associated with right-of-use assets			313,000	0
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 2,781,000	$ 0	$ 412,000	$ 150,000
Weighted-average remaining lease term - operating leases (months)	89 years 10 months 24 days	17 years 10 months 24 days	35 years 1 month 6 days	20 years 4 months 24 days
Weighted-average discount rate - operating leases	9.05%	5.67%	9.00%	6.00%

CONTRACT ASSETS AND LIABILITIES - Movement in Contract Liabilities (FY) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
The movement in the contract liabilities during each period comprised the following:
Contract liabilities at start of the period	$ 291	$ 450
Amounts invoiced during the period	0	18,310
Less revenue recognized during the period	(291)	(18,469)
Contract liabilities at end of the period	$ 0	$ 291

LEASES - Schedule of Lease Liability Maturity (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
2024	$ 434
2025	595	$ 124
2026	592	128
2027	504	110
Thereafter	2,278
Total lease payments	4,403	371
Less Imputed Interest	(1,259)	(47)
Present value of lease liabilities	$ 3,144	$ 324	$ 781

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDER'S EQUITY (DEFICIT) (Q1) - USD ($)
$ in Thousands

Total

Common Stock

Additional Paid-in Capital

Accumulated Deficit

17,862,108

Ending balance (in shares) at Jun. 14, 2022

$ 4,459

$ 2

$ 17,682

$ (13,225)

25,290,270

17,862,108

Increase (Decrease) in Stockholders' Equity [Roll Forward]

$ 4,459

$ 2

17,682

(13,225)

1,226

^[1]

877,193

475,421

140

$ (13,076)

(13,076)

26,659,711

Beginning balance (in shares) at Jun. 14, 2022

$ (3,628)

$ 3

22,701

(26,332)

25,290,270

Increase (Decrease) in Stockholders' Equity [Roll Forward]

135,090

26,659,711

Increase (Decrease) in Stockholders' Equity [Roll Forward]

$ (3,628)

$ 3

22,701

(26,332)

162

281,130

113

Ending balance (in shares) at Mar. 31, 2023

$ (2,262)

(2,262)

26,940,841

Ending balance at Mar. 31, 2023

$ (5,615)

$ 3

22,976

(28,594)

Beginning balance (in shares) at Dec. 31, 2022

26,659,711

Beginning balance at Dec. 31, 2022

$ (3,628)

$ 3

22,701

(26,332)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

821

^[2]

436,260

^[2]

$ 56

727,233

$ 274

274

Ending balance (in shares) at Dec. 31, 2023

$ (10,233)

(10,233)

45,339,762

Ending balance at Dec. 31, 2023

$ (8,674)

$ 4

27,887

(36,565)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

195

^[2]

255,102

^[2]

$ 37

Ending balance (in shares) at Mar. 31, 2024

$ 417

417

45,594,864

Ending balance at Mar. 31, 2024

$ (8,025)

$ 4

$ 28,119

$ (36,148)

[1]	Common shares issued to satisfy a fee for the Cantor Equity Facility
[2]	Common shares issued in exchange for services rendered

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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NET LOSS PER SHARE (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

NET LOSS PER SHARE

NOTE 19 – NET INCOME (LOSS) PER SHARE

As of March 31, 2024 and 2023, there were 45,594,864 and 26,940,841 shares of common stock issued and outstanding, respectively.

Basic net income (loss) per share is computed by dividing the net income (loss) by the weighted-average number of shares of common stock outstanding during the period on a basic and diluted basis.

The following table reconciles actual basic and diluted income (loss) per share for the three months ended March 31, 2024 and 2023, respectively (in thousands, except share and per share data).

	Three Months Ended March 31,
	2024	2023
Numerator:
Net income (loss) for basic net income (loss) calculation	$417	$(2,262)
Effect of dilutive securities:
Interest expense on Convertible Notes	85	—
Net income (loss) for diluted net income (loss) calculation	$502	$(2,262)

	Three Months Ended March 31,
	2024	2023
Denominator
Denominator for basic net income (loss) per share, weighted average	45,432,272	26,803,839
Effect of dilutive securities:
Convertible notes stock conversion, weighted average as converted	31,882,784	—
Denominator for diluted net income per share	77,315,056	26,803,839
Net income (loss) per common share
Basic	$0.01	$(0.08)
Diluted	$0.01	$(0.08)

	Three Months Ended March 31,
	2024	2023
Shares unvested and subject to exercise of stock options	13,896	120,431
Shares subject to outstanding common stock options	2,255,034	2,945,020
Shares subject to convertible notes stock conversion	—	695,261
Shares subject to warrants stock conversion	16,000,000	16,586,980
Shares subject to contingent earn out	10,500,000	10,500,000
Restricted stock units	2,161,509	1,314,000

NOTE 20 – NET LOSS PER SHARE

Given the consummation of the business combination, ASC 805, Business Combination states that the equity structure for the prior period of Legacy SpringBig (the accounting acquirer) is restated using the exchange ratio established in the acquisition agreement to reflect the number of shares of the accounting acquiree issued in the business combination.

As of December 31, 2023 and 2022, there were 45,339,762 and 26,659,711 shares of common stock issued and outstanding, respectively.

Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential shares of common stock. Basic and diluted net loss per share was the same for each period presented, given that there are losses during the period, the inclusion of all potential common shares outstanding would have been anti-dilutive.

The following table reconciles actual basic and diluted earnings per share for the years ended December 31, 2023 and 2022, respectively (in thousands, except share and per share data).

	Years Ended December 31,
	2023	2022
Loss per share:
Numerator:
Net loss	$(10,233)	$(13,076)
Denominator
Weighted-average common shares outstanding
Basic and diluted	36,147,187	22,287,828
Net loss per common share
Basic and diluted	$(0.28)	$(0.59)

The anti-dilutive securities excluded from the weighted-average shares used to calculate the diluted net loss per common share for the years ended December 31, 2023 and 2022 were as follows:

	Years Ended December 31,
	2023	2022
Shares unvested and subject to exercise of stock options	27,792	144,517
Shares subject to outstanding common stock options	2,244,102	3,250,236
Shares subject to convertible notes stock conversion	5,111,929	816,667
Shares subject to warrants stock conversion	16,586,980	16,586,980
Shares subject to contingent earn out	10,500,000	10,500,000
Restricted stock units	2,211,509	725,000

STOCK BASED COMPENSATION - Schedule of Restricted Stock Units Outstanding (FY) (Details) - Restricted Stock Units Outstanding - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Number of RSUs
Outstanding beginning balance (in shares)	2,211,509	725,000	0
RSUs granted (in shares)		1,989,000	761,500
RSUs forfeited (in shares)	(50,000)	(276,836)	(36,500)
RSUs vested and common stock issued (in shares)		(225,655)
Outstanding ending balance (in shares)	2,161,509	2,211,509	725,000
Weighted Average Fair Value (Per Share)
Outstanding beginning balance (in dollars per share)	$ 0.8	$ 1.97
RSUs granted (in dollars per share)		0.56	$ 1.97
RSUs forfeited (in dollars per share)	0.8	1.28	1.97
RSUs vested and common stock issued (in dollars per share)		1.97
Outstanding ending balance (in dollars per share)	$ 0.79	$ 0.8	$ 1.97
Weighted Average Vesting (Years)	1 year 10 months 24 days	2 years 2 months 12 days	2 years 6 months

PROPERTY AND EQUIPMENT (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

PROPERTY AND EQUIPMENT

NOTE 5 – PROPERTY AND EQUIPMENT

Property and equipment consist of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Computer equipment	$448	$416
Furniture & fixtures	176	149
Data warehouse	286	286
Software	197	197
Total cost	1,107	1,048
Less accumulated depreciation and amortization	(782)	(728)
Property and equipment, net	$325	$320

The useful life of computer equipment, software, furniture and fixtures, and the data warehouse is three years.

NOTE 5 – PROPERTY AND EQUIPMENT

Property and equipment consist of the following (in thousands):

	December 31,
	2023	2022
Computer equipment	$416	$333
Furniture and fixtures	149	15
Data warehouse	286	286
Software	197	197
Total Cost	1,048	831
Less accumulated depreciation and amortization	(728)	(456)
Property and Equipment	$320	$375

The useful life of computer equipment, furniture and fixtures, software and the data warehouse is 3 years.

SUBSEQUENT EVENTS (Q1)	3 Months Ended	12 Months Ended
SUBSEQUENT EVENTS (Q1)	Mar. 31, 2024	Dec. 31, 2023
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	NOTE 22 – SUBSEQUENT EVENTS Management has considered subsequent events through May 14, 2024, the date this report was issued, and there were no events that required additional disclosure.	NOTE 23 – SUBSEQUENT EVENTS On January 16, 2024, the Company entered into an agreement with LI Capital Global Opportunities to repurchase the entire outstanding principal of the Secured Convertible Note and cancel the associated warrants. The outstanding principal and accrued interest at the time of repurchase was $5.2 million. SpringBig, using a portion of the proceeds from the 8% Convertible Notes purchased the entire outstanding obligation to LI Capital Global Opportunities for $2.9 million. After the end of the fiscal year, on January 23, 2024, the Company raised $6.4 million through the issuance of 8% Convertible Notes and $1.6 million through the issuance of 12% Term Notes. The net cash proceeds, after transaction expenses, were $7.5 million. The 8% Convertible Notes accrue interest at 8% per annum which is added to the outstanding principal balance annually. The Notes are convertible into common stock at a conversion price of $0.15 per share at the holder's option any time up to the day prior to maturity in January 2026. The 12% Term Notes, due in January 2026, accrue interest payable at 12% per annum in cash semi-annually. The 8% Convertible Notes and 12% Term Notes rank pari passu and are secured by substantially all the assets of the Company. Jeffrey Harris, CEO, Paul Sykes, CFO, and Jon Trauben, Director, agreed to purchase the Convertible Notes and Term Notes for an aggregate amount of $450,000 on the same terms as all other purchasers.

BENEFIT PLAN (Q1)	3 Months Ended	12 Months Ended
BENEFIT PLAN (Q1)	Mar. 31, 2024	Dec. 31, 2023
Postemployment Benefits [Abstract]
BENEFIT PLAN	NOTE 20 – BENEFIT PLAN The Company maintains a safe harbor 401(k) retirement plan for the benefit of its employees. The plan allows participants to make contributions subject to certain limitations. Company matching contributions were $96,000 and $158,000 for the three months ended March 31, 2024 and 2023, respectively.	NOTE 21 – BENEFIT PLAN The Company maintains a safe harbor 401(k) retirement plan for the benefit of its employees. The plan allows participants to make contributions subject to certain limitations. Company matching contributions were $529,000 and $502,000 for the years ended December 31, 2023 and 2022, respectively.

The entire disclosure for retirement benefits.

PROPERTY AND EQUIPMENT - Summary (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total Cost	$ 1,107	$ 1,048	$ 831
Less accumulated depreciation and amortization	(782)	(728)	(456)
Property and Equipment, net	325	320	375
Computer equipment
Property, Plant and Equipment [Line Items]
Total Cost	448	416	333
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total Cost	176	149	15
Data warehouse
Property, Plant and Equipment [Line Items]
Total Cost	286	286	286
Software
Property, Plant and Equipment [Line Items]
Total Cost	$ 197	$ 197	$ 197

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (FY) (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Principles of Consolidation	The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.	The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Basis of Presentation	The financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).	The financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).
Foreign Currency	Foreign Currency We translate the condensed consolidated financial statements of our foreign subsidiaries, which have a functional currency in the respective country’s local currency, to U.S. dollars using month-end exchange rates for assets and liabilities and actual exchange rates for revenue, costs and expenses on the date of the transaction.	Foreign Currency We translate the financial statements of our foreign subsidiaries, which have a functional currency in the respective country’s local currency, to U.S. dollars using month-end exchange rates for assets and liabilities and actual exchange rates for revenue, costs and expenses on the date of the transaction. Translation gains and losses are included within “general and administrative expense” on the consolidated statements of operations. These gains and losses are immaterial to the financial statements.
Use of Estimates	Use of Estimates The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and revenues and expenses during the period reported. Certain accounting policies involve a “critical accounting estimate” because they are particularly dependent on estimates and assumptions made by management about matters that are highly uncertain at the time the accounting estimates are made. In addition, while we have used our best estimates based on facts and circumstances available to us at the time, different acceptable assumptions would yield different results. Changes in the accounting estimates are reasonably likely to occur from period to period, which may have a material impact on the presentation of our financial condition and results of operations. We review these estimates and assumptions periodically and reflect the effects of revisions in the period that they are determined to be necessary. We believe that the assumptions and estimates associated with income taxes, equity-based compensation (including issuance of common stock for services rendered), and allowance for credit losses have the greatest potential impact on our consolidated financial statements. Therefore, we consider the policies related to these financial areas to be our critical accounting policies. Future events and their effects cannot be predicted with certainty; accordingly, accounting estimates require the exercise of judgment. Accounting estimates used in the preparation of these financial statements change as new events occur, as more experience is acquired, as additional information is obtained, and as the operating environment changes. Actual results may differ materially from these estimates.	Use of Estimates The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and revenues and expenses during the period reported. Certain accounting policies involve a “critical accounting estimate” because they are particularly dependent on estimates and assumptions made by management about matters that are highly uncertain at the time the accounting estimates are made. In addition, while we have used our best estimates based on facts and circumstances available to us at the time, different acceptable assumptions would yield different results. Changes in the accounting estimates are reasonably likely to occur from period to period, which may have a material impact on the presentation of our financial condition and results of operations. We review these estimates and assumptions periodically and reflect the effects of revisions in the period that they are determined to be necessary. We believe that the assumptions and estimates associated with income taxes, equity-based compensation, and allowance for credit losses have the greatest potential impact on our consolidated financial statements. Therefore, we consider the policies related to income taxes, equity-based compensation, and allowance for credit losses to be our critical accounting policies. Future events and their effects cannot be predicted with certainty; accordingly, accounting estimates require the exercise of judgment. Accounting estimates used in the preparation of these financial statements change as new events occur, as more experience is acquired, as additional information is obtained, and as the operating environment changes. Actual results may differ materially from these estimates.
Segments	Segments The Company manages its business as a single operating segment. Our chief operating decision maker reviews financial information presented for the purposes of allocating resources and evaluating financial performance at an entity level and we have no segment managers who are held accountable by the chief operating decision maker for operations and operating results. The products and services across the Company are similar in nature, distributed in a comparable manner and have customers with common characteristics. We determined that we have one operating and reportable segment in accordance with Accounting Standards Codification (“ASC”) 280, Segment Reporting.	Segments The Company manages its business as a single operating segment. Our chief operating decision maker reviews financial information presented for the purposes of allocating resources and evaluating financial performance at an entity level and we have no segment managers who are held accountable by the chief operating decision maker for operations and operating results. The products and services across the company are similar in nature, distributed in a comparable manner and have customers with common characteristics. We determined that we have one operating and reportable segment in accordance with Accounting Standards Codification (“ASC”) 280, Segment Reporting.
Fair Value Measurements	Fair Value of Financial Instruments Our financial assets, which include cash equivalents, current financial assets and our current financial liabilities have fair values that approximate their carrying value due to their short-term maturities.	Fair Value of Financial Instruments Our financial assets, which include cash equivalents, current financial assets and our current financial liabilities have fair values that approximate their carrying value due to their short-term maturities.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject us to concentration of credit risk consist principally of cash and cash equivalents and accounts receivable. We place our cash and cash equivalents with high credit-quality financial institutions. Such deposits may be in excess of federally insured limits. To date, we have not experienced any losses on our cash and cash equivalents. We perform periodic evaluations of the relative credit standing of the financial institutions. We perform ongoing credit evaluations of our customers’ financial condition and require no collateral from our customers. We maintain a credit loss reserve for expected credit losses based upon the expected collectability of accounts receivable balances. See Effective Accounting Pronouncements within this Note below for further information.	Concentrations of Credit Risk Financial instruments that potentially subject us to concentration of credit risk consist principally of cash and cash equivalents and accounts receivable. We place our cash and cash equivalents with high credit-quality financial institutions. Such deposits may be in excess of federally insured limits. We perform periodic evaluations of the relative credit standing of the financial institutions. We perform ongoing credit evaluations of our customers’ financial condition and require no collateral from our customers. We maintain an allowance for credit losses based upon the expected collectability of accounts receivable balances.
Transaction Costs and Business Combinations		Transaction Costs The Company incurred significant costs direct and incremental to the business combination and therefore to the recapitalization of the Company. We deferred such costs incurred in 2021. In 2022, upon closing of the business combination, total direct transaction costs were allocated between equity and liability instruments measured at fair value on a recurring basis that were newly issued in the recapitalization. Amounts allocated to equity were recorded to additional paid-in capital, while amounts allocated to the specified liabilities were recorded as other expense. See Note 9, Business Combinations, to these consolidated financial statements for further information. Business Combinations Acquisitions of subsidiaries are accounted for using the acquisition method. The consideration for each acquisition is measured at the aggregate of the fair values (at the date of acquisition) of assets transferred and liabilities incurred or assumed, and equity instruments issued by the Company. Acquisition-related costs are recognized in the statements of operations in the period which they are incurred. Where applicable, the consideration for the acquisition includes any asset or liability resulting from a contingent consideration arrangement, measured at its acquisition-date fair value. Subsequent changes in such fair values are adjusted against the cost of acquisition where they qualify as measurement period adjustments. All other subsequent changes in the fair value of contingent consideration classified as an asset or liability are accounted for in accordance with relevant guidance consistent with ASC 805, Business Combinations. If the initial accounting for a business combination is incomplete by the end of the reporting period in which the combination occurs, the Company will report provisional amounts for the items for which the accounting is incomplete. Those provisional amounts are adjusted during the measurement period, or additional assets or liabilities are recognized, to reflect new information obtained about facts and circumstances that existed as of the acquisition date that, if known, would have affected the amounts recognized as of that date. The measurement period is the period from the date of acquisition to the date the Company obtains complete information about facts and circumstances that existed as of the acquisition date and does not exceed twelve months. The business combination was accounted for as a “reverse recapitalization.” A reverse recapitalization does not result in a new basis of accounting, and the financial statements of the combined entity represent the continuation of the financial statements of Legacy SpringBig in many respects. Under this method of accounting, Tuatara was treated as the “acquired” company for financial reporting purposes. For accounting purposes, Legacy SpringBig was deemed to be the accounting acquirer in the transaction and, consequently, the transaction was treated as a recapitalization of Legacy SpringBig (i.e., a capital transaction involving the issuance of stock by Tuatara for stock of Legacy SpringBig). Accordingly, the consolidated assets, liabilities and results of operations of Legacy SpringBig became the historical financial statements of the combined company, and Tuatara’s assets, liabilities and results of operations were consolidated with Legacy SpringBig beginning on the acquisition date. Operations prior to the business combination are presented as those of Legacy SpringBig. The net assets of Tuatara were recognized at historical cost (which are consistent with carrying value), with no goodwill or other intangible assets recorded.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less, when acquired, to be cash equivalents. The Company maintains its cash with three commercial banks.	Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less, when acquired, to be cash equivalents. The Company maintains its cash with three commercial banks. As of December 31, 2023, the Company’s cash balances in interest and non-interest bearing deposit accounts were below the federally insured limits of $250,000 per financial institution. We monitor the financial condition of such institution and have not experienced any losses associated with these accounts.
Allowance for Credit Losses	Allowance for Credit Losses The Corporation's reserve methodology used to determine the appropriate level of the allowance for credit losses (“ACL”) is a critical accounting estimate. The ACL is maintained at a level believed to be appropriate to provide for the current credit losses expected to be incurred related to the Company’s accounts and unbilled receivables at the balance sheet date. The evaluation of expected losses is based on the probability of default using historical loss rates, as well as adjustments for forward-looking information, including industry and macroeconomic forecasts, as required. Management's current methodology includes utilizing a historical loss rate equivalent to the average loss rate during the preceding forty-eight months and applying this rate to accounts and unbilled receivables at the date of recording. This rate as well as the various quantitative and qualitative factors used in the methodologies are reviewed quarterly.	Allowance for Credit Losses The Corporation's reserve methodology used to determine the appropriate level of the allowance for credit losses (“ACL”) is a critical accounting estimate. The ACL is maintained at a level believed to be appropriate to provide for the current credit losses expected to be incurred related to the Company’s accounts and unbilled receivables at the balance sheet date. The evaluation of expected losses is based on the probability of default using historical loss rates, as well as adjustments for forward-looking information, including industry and macroeconomic forecasts, as required. Management's current methodology includes utilizing a historical loss rate equivalent to the average loss rate during the preceding forty-eight months and applying this rate to accounts and unbilled receivables at the date of recording. This rate as well as the various quantitative and qualitative factors used in the methodologies are reviewed quarterly.
Property and Equipment		Property and Equipment Property and equipment are carried at cost less accumulated depreciation. Major additions and improvements which extend the life of the assets are capitalized whereas maintenance and repairs, which do not improve or extend the life of the respective assets, are expensed as incurred. When property or equipment is sold or otherwise disposed of, the related cost and accumulated depreciation are removed from the accounts and any gain or loss is included in income. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized over the shorter of their estimated useful lives or the terms of the leases.
Contract Assets (Deferred Commission), Contract Liabilities (Deferred Revenue), Revenue Recognition and Cost of Revenue		Contract Assets (Deferred Commission) The Company recognized a contract asset for the incremental costs (i.e., sales commissions) of obtaining a contract because the Company expects to recover those costs through future fees for the services to be provided. The Company amortizes the asset over the course of three years, which is the estimated number of years a customer is retained. Contract Liabilities (Deferred Revenue) The Company records contract liabilities when cash payments are received in advance of performance obligations being performed for initial start-up fees and payments received in advance of credits utilized. The Company expects to recognize these contract liabilities in the following period when it transfers its services and, therefore, satisfies its performance obligation to the customers. Revenue Recognition The Company follows the provisions of FASB Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers, which provides guidance on the recognition, presentation, and disclosure of revenue in financial statements. ASC 606 outlines the basic criteria that must be met to recognize revenue and provides guidance for disclosure related to revenue recognition policies. The Company recognizes revenue upon transfer of control of promised services to customers in an amount that reflects the consideration the Company expects to receive in exchange for those services. We report revenue net of sales and other taxes collected from customers to be remitted to government authorities. For a standard contract, the Company works with a customer to provide access to an integrated platform that provides all the functions of its proprietary software, which utilizes proprietary technology to send text or email messages to the customer’s contacts based on a credit system. Through this software, the Company allows merchants to provide loyalty plans and rewards directly to consumers through an internet portal and mobile applications. The functions of the software themselves do not have individual value to the customer. Each customer is buying the license to the platform to receive all the benefits of the platform. Therefore, the Company’s single performance obligation is to provide customers the ability to use its proprietary software application that provides marketing and customer engagement services to cannabis dispensaries throughout the United States and Canada. Nature of Promises to Transfer - The services provided by the Company’s software are subscription based for its retail and brand customers as follows: Retail customers - the Company provides its retail customer access to the software for an initial contract that is initially for a term of one year, with automatic annual renewals. Revenue is earned monthly, which consists of the contracted monthly fixed fee for software access and a specified volume of messaging credits plus, if any, optional purchases for additional credits. Brand customers - a customer can purchase use of the Company’s software, which includes a certain amount of messaging credits to be utilized over a specified period of time. The Company recognizes revenue monthly based on the credits used each month. Timing of Satisfaction - Control of services is transferred during a subscription period. Services provided by the Company are performed over time on a monthly basis for retail customers and over a designated contract term generally from six to twelve months. Allocating the Transaction Price - The transaction price of a subscription is the amount of consideration to which the Company expects to be entitled in exchange for transferring promised services to a customer. Transaction prices do not include amounts collected on behalf of third parties (e.g., sales taxes). To determine the transaction price of a contract, the Company considers its customary business practices as well as the terms of the contract. For the purpose of determining transaction prices, the Company assumes that the services will be transferred to the customer as promised in accordance with existing contracts and that the contracts will not be cancelled, renewed, or modified. The Company’s contracts with customers have fixed transaction prices that are denominated in U.S. and Canadian dollars. Consideration paid for services that customers purchase from the Company is nonrefundable. Therefore, at the time revenue is recognized, the Company does not estimate expected refunds for services. Customer discounts are netted against revenue and are recognized as incurred. For both retail and brand contracts, there is only one performance obligation for the standard contract. As such, the transaction price is allocated entirely to that obligation. Practical Expedients - The Company has adopted certain practical expedients. The Company has elected to apply the portfolio approach practical expedient to evaluate contracts with customers that share the same revenue recognition patterns as the result of evaluating them as a group will have substantially the same result as evaluating them individually. Cost of Revenues Cost of revenues principally consists of amounts payable to distributors of messages on behalf of customers across cellular networks and the cost of third-party data and integrations.
Capitalized Software Development Costs, Technology and Software Development		Capitalized Software Development Costs Internal and external costs associated with the development stage of computer applications, as well as for upgrades and enhancements that result in additional functionality of the applications, are capitalized in accordance with Accounting Standards Codification (“ASC”) 350-40, Internal-Use Software Accounting and Capitalization. Internal and external training and maintenance costs are charged to expense as incurred or over the related service period. When a software application is placed in service, the Company begins amortizing the related capitalized software costs using the straight-line method based on its estimated useful life, which is generally three years. Technology and Software Development Technology and software development expense consist primarily of personnel and related costs, including salaries, benefits, bonuses and cost of server usage by our developers.
Impairment of Long-Lived Assets		Impairment of Long-Lived Assets The Company reviews the carrying value of property and equipment for impairment whenever events and circumstances indicate that the carrying value of an asset may not be recoverable from the estimated future cash flows expected to result from its use and eventual disposition. In cases where undiscounted expected future cash flows are less than the carrying value, an impairment loss is recognized equal to an amount by which the carrying value exceeds the fair value of assets. The factors considered by management in performing this assessment include current operating results, trends, and prospects, as well as the effects of obsolescence, demand, competition, and other economic factors. The Company recognized an impairment loss on capitalized software costs of approximately $116,000 as a result of an unsuccessful application implementation. There were no impairment losses recognized in 2022.
Intangible Assets		Intangible Assets We account for intangible assets under ASC 350, Goodwill and Other. Intangible assets represent software acquired in the acquisition of Beaches Development Group. The amount is recorded at fair value on the date of the acquisition and amortized over its useful life of 3 years, using the straight-line method. The amount for intangible assets is included in property and equipment on the balance sheets.
Deferred Payroll Tax Credits		Deferred Payroll Tax Credits The Company may be eligible to receive certain payroll tax credits as a result of governmental legislation. Due to the complexities in calculating and qualifying for payroll tax credits, any benefits we may receive are uncertain and may significantly differ from our current estimates. Accordingly, we record any benefits related to these types of credits upon both the receipt of the benefit and the resolution of the uncertainties, including, but not limited to, the completion of any potential audit or examination, or the expiration of the related statute of limitations.
Selling, Servicing and Marketing Expenses, General and Administrative Expenses		Selling, Servicing and Marketing Expenses Selling, servicing and marketing expenses consist primarily of personnel and related costs, including salaries, benefits, bonuses, commissions and travel for our sales team, client success and marketing team. Other costs included in this expense are marketing and promotional events. Advertising costs are charged to marketing expense as incurred. Advertising costs were $36,000 and $174,000 for the years ended December 31, 2023 and December 31, 2022, respectively. General and Administrative Expenses General and administrative expenses consist primarily of personnel and related costs for our executive, finance, legal, human resources, and administrative personnel, including salaries, benefits, bonuses, and stock-based compensation, legal, accounting, other professional service fees and other corporate expenses.
Stock-Based Compensation		Stock-Based Compensation ASC 718, Compensation - Stock Compensation, addresses accounting for share-based awards, including stock options, restricted stock, performance shares and warrants. Stock-based compensation for stock options to employees and non-employees is based upon the fair value of the award on the date of grant. We record forfeitures as they occur. The compensation cost is recognized over the requisite service period, which is generally the vesting period, and is included in general and administrative expenses in the consolidated statements of operations. Stock-based compensation for restricted stock is based on the fair value at the date of grant and recognized over the vesting period. The Company estimates the fair value of stock options using the Black-Scholes valuation model. The expected life represents the term the options granted are expected to be outstanding. The expected volatility was determined using the historical volatility of similar publicly traded companies. The risk-free interest rate is based on the U.S. Treasury rate in effect at the time of grant.
Earnings Per Share	Basic net income (loss) per share is computed by dividing the net income (loss) by the weighted-average number of shares of common stock outstanding during the period on a basic and diluted basis.	Earnings Per Share The Company computes net income per share in accordance with ASC 260, Earnings Per Share. Under the provisions of ASC 260, basic net income per share is computed by dividing the net income available to common shareholders by the weighted average common shares outstanding during the period. Diluted net income per share adjusts basic net income per share for the effects of stock options, warrants, convertible notes and restricted stock awards only in periods, or for such awards in which the effect is dilutive. ASC 260 also requires the Company to present basic and diluted earnings per share information separately for each class of equity instruments that participate in any income distribution with primary equity instruments.
Income Taxes		Income Taxes We record current income taxes based on our estimates of current taxable income and provide for deferred income taxes to reflect estimated future income tax payments and receipts. We are subject to federal income taxes as well as state taxes. In addition, we are subject to taxes in the foreign jurisdictions where we operate. The Company records a deferred tax asset or liability based on the difference between financial statement and tax basis of assets and liabilities as measured by the anticipated tax rates which will be in effect when these differences reverse. The measurement of deferred tax assets is reduced, if necessary, by the amount of any tax benefits that, based on available evidence, are not expected to be realized. The Company adopted ASU 2016-17, Balance Sheet Classification of Deferred Taxes. The guidance requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. As a result, each jurisdiction will only have one net noncurrent deferred tax asset or liability. The Company has evaluated its tax positions for any uncertainties based on the technical merits of the positions taken. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be upheld on examination by taxing authorities. The Company has analyzed the tax positions taken and has concluded that as of December 31, 2023 and 2022, there are no uncertain tax positions taken, or expected to be taken, that would require recognition of a liability or disclosure in the financial statements.
Effective Accounting Pronouncements and Recent Accounting Pronouncements Not Yet Adopted		Effective Accounting Pronouncements In January 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. The amendments in this update modify the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. This update is effective beginning after December 15, 2021. We adopted this standard on January 1, 2022. The adoption of this standard did not have a material impact on our consolidated financial statements for the period ended December 31, 2023 or 2022. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740) - Simplifying the Accounting for Income Taxes. The ASU enhances and simplifies various aspects of the income tax accounting guidance in ASC 740, including requirements related to the following: (1) hybrid tax regimes; (2) tax basis step-up in goodwill obtained in a transaction that is not a business combination; (3) separate financial statements of entities not subject to tax; (4) intra-period tax allocation exception to the incremental approach; (5) ownership changes in investments; (6) interim-period accounting for enacted changes in tax law; and (7) year-to-date loss limitation in interim-period tax accounting. The amendments in ASU 2019-12 are effective for public business entities for fiscal years beginning after December 15, 2020, including interim periods therein. This update is effective beginning after December 15, 2021. We adopted this standard on January 1, 2022. The adoption of this standard did not have a material impact on our consolidated financial statements for the period ended December 31, 2023 or 2022. In January 2020, the FASB issued ASU 2020-01, Clarifying the Interactions between Topic 321, Topic 323, and Topic 815. The amendments in this update clarify certain interactions between the guidance to account for certain equity securities. This update is effective beginning after December 15, 2021. We adopted this standard on January 1, 2022. The adoption of this standard did not have a material impact on our consolidated financial statements for the period ended December 31, 2023 or 2022. In August 2020, the FASB issued ASU 2020-06, Accounting for Convertible Instruments and Contracts in an Entity's Own Equity. Under ASU 2020-06, embedded conversion features are no longer separated from the host contract for convertible instruments with conversion features that are not required to be accounted for as derivatives, or that do not result in substantial premiums accounted for as paid-in capital. The convertible debt instruments will now be accounted for as a single liability measured at amortized cost. This results in the interest expense recognized for convertible debt instruments to be closer to the coupon interest rate. The new guidance also requires the if-converted method to be applied for all convertible instruments when calculating earnings per share. This update is effective beginning after December 15, 2021. We adopted this standard on January 1, 2022. The adoption of this standard did not have a material impact on our consolidated financial statements for the period ended December 31, 2023 or 2022. In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842). FASB issued ASU 2016-02 to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. Certain qualitative and quantitative disclosures are required, as well as a retrospective recognition and measurement of impacted leases. In June 2020, FASB issued ASU 2020-05, Revenue from Contracts with Customers (Topic 606) and Leases (Topic 842): Deferral of the Effective Dates for Certain Entities, which deferred the effective date of ASU 2016-02 to annual reporting periods beginning after December 15, 2021, with early adoption permitted. In July 2021, the FASB released Update No. 2021-05 Lessors-Certain Leases with Variable Lease Payments. The amendments in this update affect lessors with lease contracts that (1) have variable lease payments that do not depend on a reference index or a rate and (2) would have resulted in the recognition of a selling loss at lease commencement if classified as sales-type or direct financing. The amendments in this update amend Topic 842. The amendments are effective for fiscal years beginning after December 15, 2021, for all entities, and interim periods within those fiscal years for public business entities and interim periods within fiscal years beginning after December 15, 2022, for all other entities. The Company adopted this standard on January 1, 2022. As such, we determine if an arrangement is a lease at inception. The Company recognizes a right-of-use (ROU) asset and a lease liability for operating and finance leases by recognizing and measuring leases at the commencement date based on the present value of lease payments over the lease term. The Company does not have any sales-type leases, for which the book value of the leased asset would be removed from the balance sheet and a net investment in sales-type lease would be recognized based on fixed payments under the contract and the residual value of the asset being leased. The Company has elected not to apply the recognition requirements to short-term leases and not to separate nonlease components from associated lease components for all classes of underlying assets. ROU assets are included in non-current assets and lease liabilities are included in current and non-current liabilities on the Company’s consolidated balance sheets. Operating lease expense is included in general and administrative expense on SpringBig’s consolidated statements of operations. See Note 17, Leases, to these consolidated financial statements for further information on the adoption of this accounting standard. In October 2021, the FASB issued ASU 2021-08 - Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. The amendments in this update require that an entity (acquirer) recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606. At the acquisition date, an acquirer should account for the related revenue contracts in accordance with Topic 606 as if it had originated the contracts. For public business entities, the amendments in this update are effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The amendments in this update should be applied prospectively to business combinations occurring on or after the effective date of the amendments. Early adoption of the amendments is permitted, including adoption in an interim period. An entity that early adopts in an interim period should apply the amendments (1) retrospectively to all business combinations for which the acquisition date occurs on or after the beginning of the fiscal year that includes the interim period of early application and (2) prospectively to all business combinations that occur on or after the date of initial application. We adopted this standard on January 1, 2023. The adoption of this standard did not have a material impact on our consolidated financial statements for the period ended December 31, 2023. In June 2016, FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, to revise the criteria for the measurement, recognition, and reporting of credit losses on financial instruments to be recognized when expected. In November 2019, FASB issued ASU 2019-10, Financial Instruments-Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842), which deferred the effective date of ASU 2016-13 to annual reporting periods beginning after December 15, 2022, with early adoption permitted. We adopted this standard on January 1, 2023. The adoption of this standard did not have a material impact on our consolidated financial statements for the period ended December 31, 2023. Recent Accounting Pronouncements Not Yet Adopted In November 2023, the FASB issued ASU No. 2023-07 (Topic 280), Improvements to Reportable Segment Disclosures. The ASU primarily will require enhanced disclosures about significant segment expenses. Additionally, it requires disclosure of the title and position of the individual identified as the CODM and an explanation of how the CODM uses the reported measures of a segment’s profit or loss in assessing segment performance and deciding how to allocate resources. The ASU is effective for annual periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Adoption of the ASU should be applied retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures. In December 2023, the FASB issued ASU No. 2023-09 (Topic 740), Improvements to Income Tax Disclosures (Topic 740). The ASU requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as an expansion of other income tax disclosures. The ASU is effective on a prospective basis for annual reporting periods beginning after December 15, 2024. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures.

ACCRUED EXPENSES AND OTHER LIABILITIES - Summary (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued wages, commission and bonus	$ 270	$ 393	$ 1,145
Accrued professional fees	95	176	148
Deferred financial advisory fees	1,000	1,000	1,000
Other liabilities	402	382	261
Accrued expense and other current liabilities	$ 1,767	$ 1,951	$ 2,554

RELATED PARTY TRANSACTIONS (Q1) (Details) - USD ($)		3 Months Ended		12 Months Ended
RELATED PARTY TRANSACTIONS (Q1) (Details) - USD ($)	Jan. 23, 2024	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Technology and software development		$ 1,666,000	$ 2,300,000	$ 8,011,000	$ 11,353,000
8% Secured Convertible Notes, due January 23, 2026 \| Convertible Debt
Related Party Transaction [Line Items]
Aggregate principal amount	$ 6,400,000
Interest rate (as percent)	8.00%
12% Secured Term Notes, due January 23, 2026 \| Secured Debt
Related Party Transaction [Line Items]
Aggregate principal amount	$ 1,600,000
Interest rate (as percent)	12.00%
Majority Shareholder
Related Party Transaction [Line Items]
Technology and software development		2,000	$ 4,000	13,000	153,000
Accounts payable		2,000		2,000	3,000
Related Party
Related Party Transaction [Line Items]
Accounts payable		$ 0		$ 540,000	$ 0
Related Party \| 8% Secured Convertible Notes, due January 23, 2026 \| Convertible Debt
Related Party Transaction [Line Items]
Aggregate principal amount	$ 6,400,000
Interest rate (as percent)	8.00%
Related Party \| 12% Secured Term Notes, due January 23, 2026 \| Secured Debt
Related Party Transaction [Line Items]
Aggregate principal amount	$ 1,600,000
Interest rate (as percent)	12.00%
Mr. Sykes, CFO \| 8% Secured Convertible Notes, due January 23, 2026 \| Convertible Debt
Related Party Transaction [Line Items]
Interest rate (as percent)	8.00%
Purchases from related party	$ 25,000
Mr. Sykes, CFO \| 12% Secured Term Notes, due January 23, 2026 \| Secured Debt
Related Party Transaction [Line Items]
Interest rate (as percent)	12.00%
Purchases from related party	$ 6,250
Mr. Harris, CEO \| 8% Secured Convertible Notes, due January 23, 2026 \| Convertible Debt
Related Party Transaction [Line Items]
Interest rate (as percent)	8.00%
Purchases from related party	$ 320,000
Mr. Harris, CEO \| 12% Secured Term Notes, due January 23, 2026 \| Secured Debt
Related Party Transaction [Line Items]
Interest rate (as percent)	12.00%
Purchases from related party	$ 80,000
Director \| 8% Secured Convertible Notes, due January 23, 2026 \| Convertible Debt
Related Party Transaction [Line Items]
Interest rate (as percent)	8.00%
Purchases from related party	$ 1,300,000
Director \| 12% Secured Term Notes, due January 23, 2026 \| Secured Debt
Related Party Transaction [Line Items]
Interest rate (as percent)	12.00%
Purchases from related party	$ 5,200,000

LEASES - Schedule of Supplemental Balance Sheet Information (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Assets:
Right of use asset - operating lease	$ 3,031	$ 340	$ 750
Liabilities
Current	329	99	465
Non-current	2,815	225	316
Total Operating Lease Liabilities	$ 3,144	$ 324	$ 781

STOCK BASED COMPENSATION (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Stock Options Outstanding

The following table summarizes information on stock options outstanding as of March 31, 2024 under the Legacy Incentive Plan:

	Options Outstanding		Options Vested and Exercisable
	Number of Options	Weighted Average Exercise Price (Per Share)	Number of Options	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price (Per Share)
Outstanding Balance, January 1, 2024	2,271,894	$0.57	2,244,102	4.76	$0.56
Options granted	—
Options exercised	—	$—
Options forfeited	(2,964)	$1.26
Options cancelled	—	$—
Outstanding Balance, March 31, 2024	2,268,930	$0.57	2,255,034	4.57	$0.57

The following table summarizes information on stock options outstanding as of December 31, 2023 and 2022 under the Legacy Incentive Plan:

	Options Outstanding		Options Vested and Exercisable
Fixed Options	Number of Options	Weighted Average Exercise Price (Per Share)	Number of Options	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price (Per Share)
Outstanding Balance, January 1, 2022	6,802,437	$0.38	4,628,311	6.79	$0.24
Options exercised	(530,666)	$0.55
Options forfeited	(61,460)	$0.75
Options cancelled	(4,791)	$0.75
Outstanding Balance, June 14, 2022	6,205,520
Conversion ratio	0.5929
SpringBig Holdings options	3,679,171
Options exercised	(135,090)	$0.30
Options forfeited	(149,328)	$1.11	______	___	____
Outstanding Balance, January 1, 2023	3,394,753	$0.57	3,250,236	5.79	$0.54
Options exercised	(727,233)	$0.38
Options forfeited	(25,876)	$0.82
Options cancelled	(369,750)	$0.84
Outstanding Balance, Dec. 31, 2023	2,271,894	$0.57	2,244,102	4.76	$0.56

Schedule of Restricted Stock Units Outstanding

The following table summarizes information on Restricted Stock Units outstanding as of March 31, 2024 under the 2022 Incentive Plan:

	Restricted Stock Units Outstanding
	Number of RSUs	Weighted Average Fair Value (Per Share)	Weighted Average Vesting (Years)
Outstanding Balance, December 31, 2022	725,000	$1.97	2.5
RSUs granted	1,989,000	0.56
RSUs forfeited	(276,836)	1.28
RSUs vested and common stock issued	(225,655)	$1.97
Outstanding Balance, December 31, 2023	2,211,509	$0.80
RSUs forfeited	(50,000)	0.80
Outstanding Balance, March 31, 2024	2,161,509	$0.79	1.9

The following table summarizes information on Restricted Stock Units outstanding as of December 31, 2023 under the 2022 Incentive Plan:

	Restricted Stock Units Outstanding
	Number of RSUs	Weighted Average Fair Value (Per Share)	Weighted Average Vesting (Years)
Outstanding Balance, January 1, 2022	—
RSUs granted	761,500	$1.97
RSUs forfeited	(36,500)	$1.97
Outstanding Balance, January 1, 2023	725,000	$1.97	2.5
RSUs granted	1,989,000	$0.56
RSUs forfeited	(276,836)	$1.28
RSUs vested and common stock issued	(225,655)	$1.97
Outstanding Balance, December 31, 2023	2,211,509	$0.80	2.2

DESCRIPTION OF BUSINESS (Q1)	3 Months Ended	12 Months Ended
DESCRIPTION OF BUSINESS (Q1)	Mar. 31, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS	NOTE 1 – DESCRIPTION OF BUSINESS SpringBig Holdings, Inc. and its wholly-owned subsidiaries (the “Company,” “we,” “us,”, “our”, or “SpringBig”) developed a software platform that provides marketing and customer engagement services to cannabis dispensaries and brands throughout the United States and Canada. The Company allows merchants to provide loyalty plans and rewards directly to consumers through an internet portal and mobile applications. Our operational headquarters are in Boca Raton, Florida, with additional offices located in the United States and Canada. The Company has one direct wholly-owned subsidiary, SpringBig, Inc. On June 14, 2022 (the “Closing Date”), SpringBig Holdings, Inc. (formerly known as Tuatara Capital Acquisition Corporation (“Tuatara” or “TCAC”)), consummated the business combination of SpringBig, Inc. (“Legacy SpringBig”) and HighJump Merger Sub, Inc., the wholly-owned subsidiary of Tuatara, pursuant to the Amended and Restated Agreement of Plan Merger, dated as of April 14, 2022, as amended, by and among Tuatara, HighJump Merger Sub, Inc. and Legacy SpringBig. Prior to the closing of the business combination (the “Closing”), Tuatara changed its jurisdiction of incorporation by deregistering as a Cayman Islands exempted company and continuing and domesticating as a corporation incorporated under the laws of the State of Delaware. In connection with the Closing, the registrant changed its name from Tuatara Capital Acquisition Corporation to “SpringBig Holdings, Inc.” SpringBig will continue the existing business operations of Legacy SpringBig as a publicly traded company. Beginning June 15, 2022, the ticker symbols for the Company’s common stock and publicly traded warrants were changed to “SBIG” and “SBIGW,” respectively, and commenced trading on The Nasdaq Capital Market. On September 1, 2023, the Board of Directors of SpringBig Holdings, Inc. determined that it would not be in the best interest of the Company or its shareholders to meet the continued listing requirements of the Nasdaq Capital Market, and the Company notified the Nasdaq Stock Market LLC (“Nasdaq”) that it was withdrawing its appeal of the Nasdaq Listings Qualification staff’s delist determination dated March 7, 2023, for the Company’s failure to meet the market value of listed securities requirement in the Nasdaq Listing Rules. The Company’s common stock is now quoted for trading on the OTCQX® Best Market and its public warrants are now quoted for trading on the OTC Pink Market under their current trading symbols “SBIG” and “SBIGW,” respectively. The Company’s common stock started trading on the OTCQX® Best Market on September 6, 2023. The Company remains a reporting company under the Securities Exchange Act of 1934, as amended (the “Exchange Act”).	NOTE 1 – DESCRIPTION OF BUSINESS SpringBig Holdings, Inc. and its wholly-owned subsidiaries (the “Company,” “we,” “us,”, “our”, or “SpringBig”) developed a software platform that provides marketing and customer engagement services to cannabis dispensaries and brands throughout the United States and Canada. The Company allows merchants to provide loyalty plans and rewards directly to consumers through an internet portal and mobile applications. Our operational headquarters are in Boca Raton, Florida, with additional offices located in the United States and Canada. The Company has one direct wholly-owned subsidiary, SpringBig, Inc. On June 14, 2022 (the “Closing Date”), SpringBig Holdings, Inc. (formerly known as Tuatara Capital Acquisition Corporation (“Tuatara” or “TCAC”)), consummated the business combination of SpringBig, Inc. (“Legacy SpringBig”) and HighJump Merger Sub, Inc., the wholly-owned subsidiary of Tuatara, pursuant to the Amended and Restated Agreement of Plan Merger, dated as of April 14, 2022, as amended, by and among Tuatara, HighJump Merger Sub, Inc. and Legacy SpringBig. Prior to the closing of the business combination (the “Closing”), Tuatara changed its jurisdiction of incorporation by deregistering as a Cayman Islands exempted company and continuing and domesticating as a corporation incorporated under the laws of the State of Delaware. In connection with the Closing, the registrant changed its name from Tuatara Capital Acquisition Corporation to “SpringBig Holdings, Inc.” SpringBig will continue the existing business operations of Legacy SpringBig as a publicly traded company. See Note 9, Business Combinations, to these consolidated financial statements for further information. While the legal acquirer in the business combination is SpringBig for financial accounting and reporting purposes under U.S. GAAP, Legacy SpringBig is the accounting acquirer, with the merger accounted for as a “reverse recapitalization.” A reverse recapitalization does not result in a new basis of accounting, and the financial statements of the combined entity represent the continuation of the financial statements of Legacy SpringBig. Under this accounting method, SpringBig is treated as the “acquired” company and Legacy SpringBig is the accounting acquirer, with the transaction treated as a recapitalization of Legacy SpringBig. SpringBig’s assets, liabilities and results of operations were consolidated with Legacy SpringBig’s beginning on the date of the business combination. Except for certain warrant liabilities, the assets and liabilities of SpringBig were recognized at historical cost (which is consistent with carrying value) and were not material, with no goodwill or other intangible assets recorded. The warrant liabilities, which are discussed in Note 12, Warrant Liabilities, were recorded at fair value. The consolidated assets, liabilities, and results of operations of Legacy SpringBig became the historical financial statements, and operations prior to the closing of the business combination presented for comparative purposes are those of Legacy SpringBig. Pre-merger shares of common stock and preferred stock of Legacy SpringBig were converted to shares of common stock of the combined company using the conversion ratio of 0.59289 and for comparative purposes, the shares and net loss per share of Legacy SpringBig prior to the merger have been retroactively restated using the conversion ratio. Beginning June 15, 2022, the ticker symbols for the Company’s common stock and publicly-traded warrants were changed to “SBIG” and “SBIGW,” respectively, and commenced trading on The Nasdaq Capital Market. The Company received net proceeds of $18.8 million, with gross proceeds of $25.1 million, which were in addition to the $7.0 million in Convertible Notes proceeds, which were received in February 2022 in connection with Legacy SpringBig’s issuance of such notes (and which Convertible Notes and the interest due thereon were converted into common stock in connection with the business combination. See Note 10, 15% Convertible Promissory Notes, to these consolidated financial statements). Of the amount received at the Closing, approximately $8.8 million represented cash from the TCAC trust related to unredeemed shares; $6.1 million represented proceeds from the subscription for common stock from certain investors (the “PIPE Financing”), and $10.0 million from the Secured Convertible Note (defined below). The Company incurred additional cash and non cash expenses totaling $8.7 million, resulting in net business combination proceeds of $10.1 million. On September 1, 2023, (i) the Board of Directors of SpringBig Holdings, Inc. determined that it would not be in the best interest of the Company or its shareholders to meet the continued listing requirements of the Nasdaq Capital Market, (ii) the Company notified the Nasdaq Stock Market LLC (“Nasdaq”) that it was withdrawing its appeal of the Nasdaq Listings Qualification staff’s delist determination dated March 7, 2023, for the Company’s failure to meet the market value of listed securities requirement in Nasdaq Listing Rule 5450(b)(2)(A) and (iii) the Company received a letter from Nasdaq confirming (a) the withdrawal of the appeal, (b) as a result of the withdrawal, the Company’s common stock and public warrants would be suspended at the open of business on September 5, 2023 and (c) Nasdaq would file a Form 25 Notification of Delisting with the SEC when all of its internal procedural periods have run. The letter also noted that the Company failed to meet the minimum bid price requirement in Nasdaq Listing Rule 5450(a)(1). The Company’s common stock is now quoted for trading on the OTCQX® Best Market and its public warrants are now quoted for trading on the OTC Pink Market under their current trading symbols “SBIG” and “SBIGW,” respectively, following the delisting from trading on the Nasdaq Capital Market. The Company’s common stock started trading on the OTCQX® Best Market on September 6, 2023. The Company remains a reporting company under the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

INCOME TAXES (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Income Tax Disclosure [Abstract]

INCOME TAXES

NOTE 21 – INCOME TAXES

In determining quarterly provisions for income taxes, the Company uses the annual estimated effective tax rate applied to the actual year-to-date profit or loss, adjusted for discrete items arising in that quarter. The Company’s annual estimated effective tax rate differs from the U.S. federal statutory rate primarily as a result of state taxes, foreign taxes, and changes in the Company’s full valuation allowance against its deferred tax assets.

NOTE 22 – INCOME TAXES

U.S. and foreign components of loss from operations before income taxes were as follows (in thousands):

The provision (benefit) for income taxes consist of the following, (in thousands):

	Years Ended December 31,
	2023	2022
Provision (benefit) for income taxes
Current
Federal	$—	$—
State	4	1
International	—	2
	$4	$ 3

The Company’s actual provision (benefit) for income taxes from operations differ from the federal expected income tax provision as follows (in thousands):

	December 31, 2023		December 31, 2022
	Amount	Rate	Amount	Rate
U.S. federal income tax provision (benefit) at statutory rate	$(2,126)	21%	$(2,754)	21%
Increase (decrease) in taxes resulting from:
State income tax expense	4	5%	1	5%
Foreign income and losses taxed at different rates	(28)	1%	(68)	1%
Change in valuation allowance	2,090	(32)%	4,122	(32)%
Non-deductible or non-taxable items	37	5%	(1,302)	5%
Foreign income taxes	—	—%	2	—%
Effect of income tax rate changes on deferred items	27	—%	2	—%
Provision (benefit) for income taxes	$4	—%	$3	—%

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. In assessing the realizability of deferred tax assets, Management evaluates whether it is more likely than not that some portion or all the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. Based on Management’s evaluation, the net deferred tax asset was offset by a full valuation allowance as of December 31, 2023 and 2022, respectively. The deferred tax asset valuation allowance will be reversed if and when the Company generates sufficient taxable income in the future to utilize the tax benefits of the related deferred tax assets.

	Years Ended December 31,
	2023	2022
Deferred tax assets:
Accrued expenses and other liabilities	$771	$376
Net operating loss - US Federal	4,848	5,556
Net operating loss - US State	1,020	1,188
Net operating loss - Foreign	711	575
Property and equipment, net	—	8
Operating lease liability	82	198
Research and development	1,974	—
Stock based compensation	525	215
Total gross deferred tax assets	$9,931	$8,116
Less: valuation allowance	(9,596)	(7,506)
Total deferred tax assets	335	610
Deferred tax liabilities:
Prepaid expenses and other assets	$(231)	$(420)
Operating lease right of use asset	(79)	(190)
Property and equipment, net	(25)	—
Total deferred tax liabilities	(335)	(610)
Net deferred income tax asset (liability)	$—	$—

The Company has incurred significant losses in recent periods. As a result, we maintained valuation allowances against our domestic and foreign deferred tax assets as of December 31, 2023 and 2022, to reduce their carrying values to amounts that are realizable either through future reversals of existing taxable temporary differences or through taxable income in carryback years for the applicable jurisdictions.

At December 31, 2023, the Company has federal net operating loss available to carryforward of approximately $23.1 million which will be carried forward indefinitely. Pursuant to IRC §382 of the Internal Revenue Code, the utilization of net operating loss carryforwards may be limited as a result of a cumulative change in stock ownership of more than 50% over a three-year period. The Company has not determined whether such a change has occurred and accordingly, the utilization of the net operating loss carryforwards may be subject to certain limitations.

The Company has state and foreign net operating losses available to carryforward of approximately $23.5 million and $2.7 million, respectively, which begin expiring in 2030 and 2037, respectively, as of December 31, 2023.

The Company has evaluated its tax positions for any uncertainties based on the technical merits of the positions taken. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be upheld on examination by taxing authorities. The Company has analyzed the tax positions taken and has concluded that as of December 31, 2023 and 2022, there are no uncertain tax positions taken, or expected to be taken, that would require recognition of a liability or disclosure in the financial statements.

The Company accrues interest and penalties arising on the underpayment of taxes if the full benefit of a tax position is not recognized in the financial statements. In accordance with ASC 740, Accounting for Income Taxes, interest and penalties are recorded as income tax expense. There have been no penalties or interest paid or incurred during the twelve months ended December 31, 2023 and 2022, respectively.

Management is required to analyze all open tax years, as defined by the statute of limitations, for all major jurisdictions, including federal and certain state taxing authorities. As of and for the twelve months ended December 31, 2023 and 2022, the Company did not have a liability for any unrecognized taxes. The Company has no examinations in progress and is not aware of any tax positions for which it is reasonably possible that the total amounts of unrecognized tax liabilities will significantly change in the next twelve months. The Company’s 2019 through 2021 tax years are open for examination for federal and state taxing authorities.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

FAIR VALUE MEASUREMENTS - Schedule of Changes in Fair Value (Q1) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in fair value	$ 3,000	$ 153,000	$ (334,000)	$ (4,158,000)
Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3,000	$ 338,000	338,000	0
Changes in fair value	3,000		(335,000)	(4,158,000)
Ending balance	$ 6,000		$ 3,000	$ 338,000

FAIR VALUE MEASUREMENTS (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule Of Fair Value, Liabilities Measured on Recurring Basis

The balances of the Company’s liabilities measured at fair value on a recurring basis as of March 31, 2024, are as follows (in thousands):

	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	6	—	—	6
	$6	$—	$—	$6

The balances of the Company’s liabilities measured at fair value on a recurring basis as of December 31, 2023, are as follows (in thousands):

	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	3	—	—	3
	$3	$—	$—	$3

The balances of the Company’s liabilities measured at fair value on a recurring basis as of December 31, 2023 and 2022, are as follows (in thousands):

For the year ended December 31, 2022	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	338	—	—	338
	$338	$—	$—	$338

For the year ended December 31, 2023	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	3	—	—	3
	$3	$—	$—	$3

Schedule of Changes in Fair Value

The following tables provides a roll-forward in the changes in fair value in the public warrants for the three months ended March 31, 2024 (in thousands):

Warrants
Balance, January 1, 2024			$3
Change in fair value			3
Balance, March 31, 2024			$6
Changes in fair value included in earnings for the period relating to liabilities held at March 31, 2024			$3

Warrants
Balance, January 1, 2022			$—
Assumed in business combination at fair value			$4,496
Change in value			$(4,158)
Balance, December 31, 2022			$338
Changes in fair value included in earnings for the period relating to liabilities held at December 31, 2022			$(4,158)

Balance, January 1, 2023			$338
Change in fair value			(335)
Balance, December 31, 2023			$3
Changes in fair value included in earnings for the period relating to liabilities held at December 31, 2023			$(335)

WARRANT LIABILITIES (FY)	3 Months Ended	12 Months Ended
WARRANT LIABILITIES (FY)	Mar. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
WARRANT LIABILITIES	NOTE 11 – WARRANT LIABILITIES Prior to the business combination, at the time of their initial public offering, TCAC issued warrants to purchase 10,000,000 Class A ordinary shares at a price of $11.50 per share, for aggregate consideration of $10.0 million as part of the units offered by the prospectus and, simultaneously with the closing of their initial public offering, issued in a private placement an aggregate of 6,000,000 private placement warrants for aggregate consideration of $6.0 million, each exercisable to purchase one Class A ordinary share at a price of $11.50 per share. The Company accounts for the warrants in accordance with the guidance contained in ASC 815 Derivatives and Hedging, under which the warrants do not meet the criteria for equity treatment and hence are recorded as liabilities. Accordingly, we classify the warrants as liabilities at their fair value and adjust the warrants to fair value at each reporting period. This liability is subject to re-measurement at each balance sheet date until exercised, and any change in fair value is recognized in our statement of operations. At March 31, 2024 and December 31, 2023, the estimated fair value of the warrants was $6,400 and $3,200, respectively. The Company recorded a change in fair value loss of approximately $3,000 and $153,000 for the three months ended March 31, 2024 and 2023, respectively. The fair value is determined in accordance with ASC 820, Fair Value Measurement. See Note 17, Fair Value Measurements, to the accompanying condensed consolidated financial statements for further information.	NOTE 12 – WARRANT LIABILITIES Prior to the business combination, at the time of their initial public offering, TCAC issued warrants to purchase 10,000,000 Class A ordinary shares at a price of $11.50 per share, for aggregate consideration of $10.0 million as part of the units offered by the prospectus and, simultaneously with the closing of their initial public offering, issued in a private placement an aggregate of 6,000,000 private placement warrants for aggregate consideration of $6.0 million, each exercisable to purchase one Class A ordinary share at a price of $11.50 per share. The Company accounts for the warrants in accordance with the guidance contained in ASC 815 Derivatives and Hedging, under which the warrants do not meet the criteria for equity treatment and hence are recorded as liabilities. Accordingly, we classify the warrants as liabilities at their fair value and adjust the warrants to fair value at each reporting period. This liability is subject to re-measurement at each balance sheet date until exercised, and any change in fair value is recognized in our statement of operations. At December 31, 2023, the estimated fair value of the warrants was $3,200. At December 31, 2022, the estimated fair value of the warrants is $0.3 million. The Company recorded a change in fair value gain of approximately $0.3 million and $4.2 million for the years ended December 31, 2023 and 2022, respectively. These amounts are included in the statements of operations for the year ended December 31, 2023 and 2022. The fair value is determined in accordance with ASC 820, Fair Value Measurement. See Note 18, Fair Value Measurements, to the accompanying consolidated financial statements for further information.

CONSOLIDATED BALANCE SHEETS (Q1) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 1,668	$ 331		$ 3,546
Accounts receivable, net	3,211	2,948		2,889
Contract assets	255	273		333
Prepaid expenses and other current assets	588	893		1,505
Total current assets	5,722	4,445		8,273
Operating lease assets	3,031	340		750
Property and equipment, net	325	320		375
Total assets	9,078	5,105		9,657
Current liabilities:
Accrued expense and other current liabilities	1,767	1,951		2,554
Short-term cash advances	1,195	1,925		0
Current maturities of long-term debt	0	4,360		5,451
Deferred payroll tax credits	1,751	1,751	$ 1,400	0
Deferred revenue	2	0		291	$ 450
Operating lease liability, current	329	99		465
Total current liabilities	7,084	13,551		9,817
Long-term debt, non-current	7,198	0		2,814
Operating lease liability, non-current	2,815	225		316
Warrant liabilities	6	3		338
Total liabilities	17,103	13,779		13,285
Commitments and Contingencies
Stockholders' Deficit
Common stock par value $0.0001 per share, 300,000,000 authorized at March 31, 2024; 45,594,864 issued and outstanding as of March 31, 2024; (300,000,000 authorized at December 31, 2023; 45,339,762 issued and outstanding as of December 31, 2023)	4	4		3
Additional paid-in-capital	28,119	27,887		22,701
Accumulated deficit	(36,148)	(36,565)		(26,332)
Total stockholders' deficit	(8,025)	(8,674)	$ (5,615)	(3,628)	$ 4,459
Total liabilities and stockholders' deficit	9,078	5,105		9,657
Nonrelated Party
Current liabilities:
Accounts payable	2,040	2,925		1,056
Related Party
Current liabilities:
Accounts payable	$ 0	$ 540		$ 0

REVENUE RECOGNITION - Disaggregation of Revenue (FY) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Total Revenue	$ 6,474	$ 7,157	$ 28,050	$ 26,629
Brand revenue
Disaggregation of Revenue [Line Items]
Total Revenue	59	295	901	940
Brand revenue \| United States
Disaggregation of Revenue [Line Items]
Total Revenue	59	294	889	936
Brand revenue \| Canada
Disaggregation of Revenue [Line Items]
Total Revenue	0	1	12	4
Retail revenue
Disaggregation of Revenue [Line Items]
Total Revenue	6,415	6,862	27,149	25,689
Retail revenue \| United States
Disaggregation of Revenue [Line Items]
Total Revenue	6,273	6,663	26,372	25,075
Retail revenue \| Canada
Disaggregation of Revenue [Line Items]
Total Revenue	$ 142	$ 199	$ 777	$ 614

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

ACCOUNTS RECEIVABLE (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Accounts Receivable

Accounts receivable, net consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Accounts receivable	$4,005	$3,690
Unbilled receivables	854	853
Total receivables	4,859	4,543
Less allowance for doubtful accounts	(1,648)	(1,595)
Accounts receivable, net	$3,211	$2,948

Accounts receivable, net consisted of the following (in thousands):

	December 31,
	2023	2022
Accounts receivable	$3,690	$3,639
Unbilled receivables	853	731
Total receivables	4,543	4,370
Less allowance for credit losses	(1,595)	(1,481)
Accounts receivable, net	$2,948	$2,889

Schedule of Allowance for Credit Loss

The following table details the activity related to the Company’s allowance for credit losses for the quarter ending March 31, 2024 (in thousands).

			Allowance for credit losses
Outstanding Balance, December 31, 2023			$1,595
Current-period provision (release) for expected credit losses			53
Write-offs charged against the allowance, net of recoveries and other			—
Outstanding Balance, March 31, 2024			$1,648

The following table details the activity related to the Company’s allowance for credit losses for the years ending December 31, 2023 and 2022, respectively (in thousands).

			Allowance for credit losses
Outstanding Balance, January 1, 2023			$1,481
Current-period provision (release) for expected credit losses			1,563
Write-offs charged against the allowance, net of recoveries and other			(1,449)
Outstanding Balance, December 31, 2023			$1,595

COMMITMENTS AND CONTINGENCIES (Q1) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Amounts from deferred payroll tax credits	$ 2,000
Operating expenses offset	600
Deferred payroll tax credits	$ 1,400	$ 1,751	$ 1,751	$ 0

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS EQUITY (DEFICIT) (FY) - USD ($)
$ in Thousands

Total

Lease standard adoption

Common Stock

Additional Paid-in Capital

Accumulated Deficit

Lease standard adoption

17,862,108

Ending balance (in shares) at Jun. 14, 2022

$ 4,459

$ (31)

$ 2

$ 17,682

$ (13,225)

$ (31)

25,290,270

17,862,108

Increase (Decrease) in Stockholders' Equity [Roll Forward]

$ 4,459

$ (31)

$ 2

17,682

(13,225)

$ (31)

1,226

475,421

Recapitalization (in shares)

140

7,093,744

Recapitalization

3,454

$ 1

3,453

^[1]

877,193

^[2]

351,245

^[2]

200

Issuance of common stock

$ (13,076)

(13,076)

26,659,711

Beginning balance (in shares) at Jun. 14, 2022

$ (3,628)

$ 3

22,701

(26,332)

25,290,270

Increase (Decrease) in Stockholders' Equity [Roll Forward]

135,090

26,659,711

Increase (Decrease) in Stockholders' Equity [Roll Forward]

$ (3,628)

$ 3

22,701

(26,332)

162

281,130

113

Ending balance (in shares) at Mar. 31, 2023

$ (2,262)

(2,262)

26,940,841

Ending balance at Mar. 31, 2023

$ (5,615)

$ 3

22,976

(28,594)

Beginning balance (in shares) at Dec. 31, 2022

26,659,711

Beginning balance at Dec. 31, 2022

$ (3,628)

$ 3

22,701

(26,332)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

$ 821

821

727,233

$ 274

274

^[3]

436,260

^[2]

5,690,903

^[2]

1,450

Issuance of common stock

^[3]

^[4]

9,900,000

^[4]

2,323

$ 1

2,322

^[5]

1,700,000

^[5]

263

RSU vesting (in shares)

225,655

Ending balance (in shares) at Dec. 31, 2023

$ (10,233)

(10,233)

45,339,762

Ending balance at Dec. 31, 2023

$ (8,674)

$ 4

27,887

(36,565)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

$ 195

195

^[3]

255,102

Issuance of common stock

^[3]

$ 37

Ending balance (in shares) at Mar. 31, 2024

$ 417

417

45,594,864

Ending balance at Mar. 31, 2024

$ (8,025)

$ 4

$ 28,119

$ (36,148)

[1]	Common shares issued to satisfy a fee for the Cantor Equity Facility
[2]	Common shares issued as repayment of Senior Secured Convertible Notes
[3]	Common shares issued in exchange for services rendered
[4]	Equity raise
[5]	Common shares issued in connection with settlement of litigation

NET INCOME (LOSS) PER SHARE (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

NET INCOME (LOSS) PER SHARE

NOTE 19 – NET INCOME (LOSS) PER SHARE

As of March 31, 2024 and 2023, there were 45,594,864 and 26,940,841 shares of common stock issued and outstanding, respectively.

Basic net income (loss) per share is computed by dividing the net income (loss) by the weighted-average number of shares of common stock outstanding during the period on a basic and diluted basis.

The following table reconciles actual basic and diluted income (loss) per share for the three months ended March 31, 2024 and 2023, respectively (in thousands, except share and per share data).

	Three Months Ended March 31,
	2024	2023
Numerator:
Net income (loss) for basic net income (loss) calculation	$417	$(2,262)
Effect of dilutive securities:
Interest expense on Convertible Notes	85	—
Net income (loss) for diluted net income (loss) calculation	$502	$(2,262)

	Three Months Ended March 31,
	2024	2023
Denominator
Denominator for basic net income (loss) per share, weighted average	45,432,272	26,803,839
Effect of dilutive securities:
Convertible notes stock conversion, weighted average as converted	31,882,784	—
Denominator for diluted net income per share	77,315,056	26,803,839
Net income (loss) per common share
Basic	$0.01	$(0.08)
Diluted	$0.01	$(0.08)

	Three Months Ended March 31,
	2024	2023
Shares unvested and subject to exercise of stock options	13,896	120,431
Shares subject to outstanding common stock options	2,255,034	2,945,020
Shares subject to convertible notes stock conversion	—	695,261
Shares subject to warrants stock conversion	16,000,000	16,586,980
Shares subject to contingent earn out	10,500,000	10,500,000
Restricted stock units	2,161,509	1,314,000

NOTE 20 – NET LOSS PER SHARE

As of December 31, 2023 and 2022, there were 45,339,762 and 26,659,711 shares of common stock issued and outstanding, respectively.

The following table reconciles actual basic and diluted earnings per share for the years ended December 31, 2023 and 2022, respectively (in thousands, except share and per share data).

	Years Ended December 31,
	2023	2022
Loss per share:
Numerator:
Net loss	$(10,233)	$(13,076)
Denominator
Weighted-average common shares outstanding
Basic and diluted	36,147,187	22,287,828
Net loss per common share
Basic and diluted	$(0.28)	$(0.59)

The anti-dilutive securities excluded from the weighted-average shares used to calculate the diluted net loss per common share for the years ended December 31, 2023 and 2022 were as follows:

	Years Ended December 31,
	2023	2022
Shares unvested and subject to exercise of stock options	27,792	144,517
Shares subject to outstanding common stock options	2,244,102	3,250,236
Shares subject to convertible notes stock conversion	5,111,929	816,667
Shares subject to warrants stock conversion	16,586,980	16,586,980
Shares subject to contingent earn out	10,500,000	10,500,000
Restricted stock units	2,211,509	725,000

PROPERTY AND EQUIPMENT - Narrative (Q1) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Property and equipment, useful life (in years)	3 years		3 years
Depreciation and amortization	$ 54	$ 66	$ 272	$ 259

INCOME TAXES - Narrative (FY) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Domestic Tax Authority
Income Tax Contingency [Line Items]
Operating loss carryforwards, not subject to expiration	$ 23.1
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Operating loss carryforwards, subject to expiration	23.5
Foreign Tax Authority
Income Tax Contingency [Line Items]
Operating loss carryforwards, subject to expiration	$ 2.7

LEASES - Narrative (FY) (Details) - USD ($)	1 Months Ended	3 Months Ended		12 Months Ended
LEASES - Narrative (FY) (Details) - USD ($)	Jun. 30, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Jan. 01, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating lease assets		$ 3,031,000		$ 340,000	$ 750,000
Lease liabilities		3,144,000		324,000	781,000
Equity adjustment		(8,025,000)	$ (5,615,000)	$ (8,674,000)	(3,628,000)		$ 4,459,000
Term of contract	98 months			98 months
Gain on termination of lease				$ 14,000
Lease expense				725,000	846,000
Rent expense, other				486,000	515,000
Operating lease cost		160,000	$ 133,000	486,000	$ 515,000
Lease standard adoption
Lessee, Lease, Description [Line Items]
Equity adjustment							(31,000)
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease assets						$ 1,100,000
Lease liabilities						$ 1,100,000
Accounting Standards Update 2016-02 \| Lease standard adoption
Lessee, Lease, Description [Line Items]
Equity adjustment							$ (31,000)
Minimum
Lessee, Lease, Description [Line Items]
Monthly rent expense	$ 38,000			38,000
Minimum \| Boca Raton, Florida, Seattle, Washington And Ontario, Canada
Lessee, Lease, Description [Line Items]
Monthly rent expense		4,000		4,000
Maximum
Lessee, Lease, Description [Line Items]
Monthly rent expense	$ 48,000			48,000
Maximum \| Boca Raton, Florida, Seattle, Washington And Ontario, Canada
Lessee, Lease, Description [Line Items]
Monthly rent expense		$ 48,000		$ 7,000

PROPERTY AND EQUIPMENT - Narrative (FY) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Property and equipment, useful life	3 years		3 years
Depreciation and amortization	$ 54	$ 66	$ 272	$ 259

NET LOSS PER SHARE - Basic and Diluted Earnings Per Share (FY) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net loss	$ 417	$ (2,262)	$ (10,233)	$ (13,076)
Weighted-average common shares outstanding
Weighted-average common shares outstanding - basic (in shares)	45,432,272	26,803,839	36,147,187	22,287,828
Weighted-average common shares outstanding - diluted (in shares)	77,315,056	26,803,839	36,147,187	22,287,828
Net loss per common share, basic (in dollars per share)	$ 0.01	$ (0.08)	$ (0.28)	$ (0.59)
Net loss per common share, diluted (in dollars per share)	$ 0.01	$ (0.08)	$ (0.28)	$ (0.59)

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

Commitments and Contingencies Disclosure [Abstract]

ACCOUNTS RECEIVABLE - Narrative (Q1) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Receivables [Abstract]
Bad debt expense	$ 87	$ 169	$ 1,563	$ 1,474

COMMITMENTS AND CONTINGENCIES (FY) (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2023

USD ($)

Estimated litigation liability

$ 800

Payments for legal settlements

200

Stock issued during period, value, settlement of litigation

263

^[1]

Remaining liability

300

Litigation settlement, amount awarded to other party, periodic payments, amount

$ 40

[1]	Common shares issued in connection with settlement of litigation

ACCRUED EXPENSES AND OTHER LIABILITIES - Schedule of Accrued Expenses and Other Current Liabilities (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued wages, commission and bonus	$ 270	$ 393	$ 1,145
Accrued professional fees	95	176	148
Deferred financial advisory fees	1,000	1,000	1,000
Other liabilities	402	382	261
Accrued expense and other current liabilities	$ 1,767	$ 1,951	$ 2,554

FAIR VALUE MEASUREMENTS - Narratives (FY) (Details)	Mar. 31, 2024 USD ($) $ / shares	Dec. 31, 2023 USD ($) $ / shares	Dec. 31, 2022 USD ($) $ / shares	Jun. 14, 2022 shares	Jun. 13, 2022 $ / shares shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, noncurrent \| $	$ 6,000	$ 3,000	$ 338,000
Measurement Input, Share Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability measurement input \| $ / shares	0.0004	0.0002	0.0211
Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, noncurrent \| $	$ 6,400	$ 3,200	$ 300,000
Redeemable Warrants \| Class A common stock
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants outstanding (in shares) \| shares					10,000,000
Exercise price of warrants (in dollars per share) \| $ / shares					$ 11.5
Number of shares issuable per each warrant (in shares) \| shares				1
Private Placement Warrant
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants outstanding (in shares) \| shares				6,000,000
Exercise price of warrants (in dollars per share) \| $ / shares					$ 11.5
Public And Private Warrants \| Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability, noncurrent \| $		$ 3,200	$ 300,000

PREPAID EXPENSES AND OTHER CURRENT ASSETS (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

PREPAID EXPENSES AND OTHER CURRENT ASSETS

NOTE 4 – PREPAID EXPENSES AND OTHER CURRENT ASSETS

Prepaid expenses and other current assets consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Prepaid insurance	$109	$379
Other prepaid expenses	390	425
Deposits	89	89
	$588	$893

NOTE 4 – PREPAID EXPENSES AND OTHER CURRENT ASSETS

Prepaid expenses and other current assets consisted of the following (in thousands):

DESCRIPTION OF BUSINESS (Q1) (Details) - subsidiary	Mar. 31, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of subsidiaries	1	1

CONSOLIDATED BALANCE SHEETS (FY) (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 14, 2022
Statement of Financial Position [Abstract]
Common stock, par or stated value per share (in dollars per share)	$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	300,000,000	300,000,000		300,000,000	300,000,000
Common stock, shares, issued (in shares)	45,594,864	45,339,762	26,940,841	26,659,711	25,290,270
Common stock, shares, outstanding (in shares)	45,594,864	45,339,762	26,940,841	26,659,711	25,290,270

PROPERTY AND EQUIPMENT - Schedule of Property and Equipment (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total cost	$ 1,107	$ 1,048	$ 831
Less accumulated depreciation and amortization	(782)	(728)	(456)
Property and Equipment, net	325	320	375
Computer equipment
Property, Plant and Equipment [Line Items]
Total cost	448	416	333
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total cost	176	149	15
Data warehouse
Property, Plant and Equipment [Line Items]
Total cost	286	286	286
Software
Property, Plant and Equipment [Line Items]
Total cost	$ 197	$ 197	$ 197

REVENUE RECOGNITION - Narrative (Q1) (Details)	3 Months Ended		12 Months Ended
REVENUE RECOGNITION - Narrative (Q1) (Details)	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Geographic Concentration Risk \| Revenue from Contract with Customer Benchmark \| United States
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	98.00%	97.00%	97.00%	98.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

LEASES - Supplemental Balance Sheet Information (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Assets:
Right of Use Assets - Operating Lease	$ 3,031	$ 340	$ 750
Liabilities:
Current	329	99	465
Non-current	2,815	225	316
Total Operating Lease Liabilities	$ 3,144	$ 324	$ 781

CONVERTIBLE NOTE RECEIVABLE (Q1) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Apr. 30, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Convertible note receivable			$ 0	$ 259	$ 250
Note receivable, interest rate (as percent)					5.00%
Convertible debt			0
Impairment loss			116	0
Interest income	$ 4	$ 10	24	$ 18
Convertible Note Receivable, Accrued Interest
Financing Receivable, Allowance for Credit Loss [Line Items]
Impairment loss			272
Interest income			$ 22

SUBSEQUENT EVENTS (FY) (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		12 Months Ended
	Jan. 23, 2024	Jan. 16, 2024	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Subsequent Event [Line Items]
Purchase obligation	$ 2,900		$ 2,895	$ 1,457	$ 3,238	$ 1,000
Senior Secured Original Issue Discount Convertible Note \| Convertible Notes Payable
Subsequent Event [Line Items]
Interest rate			6.00%
8.00% Convertible Notes \| Convertible Debt
Subsequent Event [Line Items]
Interest rate	8.00%
Aggregate principal amount	$ 6,400
Conversion price (dollars per share)	$ 0.15
Term Note \| Secured Debt
Subsequent Event [Line Items]
Interest rate	12.00%
Aggregate principal amount	$ 1,600
Subsequent Event
Subsequent Event [Line Items]
Purchase obligation	2,900
Proceeds from issuance of debt	7,500
Subsequent Event \| Senior Secured Original Issue Discount Convertible Note \| Convertible Notes Payable
Subsequent Event [Line Items]
Convertible debt		$ 5,200
Purchase obligation	2,900	$ 2,900
Subsequent Event \| Convertible Notes and Term Notes \| Chief Executive Officer, Chief Financial Officer And Director
Subsequent Event [Line Items]
Aggregate principal amount	$ 450
Subsequent Event \| 8.00% Convertible Notes \| Convertible Debt
Subsequent Event [Line Items]
Interest rate	8.00%	8.00%
Aggregate principal amount	$ 6,400
Conversion price (dollars per share)	$ 0.15
Subsequent Event \| Term Note \| Secured Debt
Subsequent Event [Line Items]
Interest rate	12.00%
Aggregate principal amount	$ 1,600

LEASES (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

LEASES

NOTE 15 – LEASES

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Balance Sheet
Assets:
Right of use asset - operating lease	$3,031	$340
Liabilities
Current	329	99
Non-current	2,815	225
Total operating lease liability	$3,144	$324

	Three Months Ended March 31, 2024	Three Months Ended March 31, 2023
Other information
Operating lease cost	$160	$133
Operating cash flows paid to operating leases	$31	$126
Right-of-use assets in exchange for new operating lease liabilities	$2,781	$—
Weighted-average remaining lease term — operating leases (months)	89.9	17.9
Weighted-average discount rate — operating leases	9.05%	5.67%

As of March 31, 2024, the Company’s lease liabilities mature as follows:

Fiscal Year:			Operating Leases
2024			$434
2025			595
2026			592
2027			504
Thereafter			2,278
Total lease payments			4,403
Less Imputed Interest			(1,259)
Present value of lease liabilities			$3,144

NOTE 17 – LEASES

The Company leases office facilities in Boca Raton, Florida, Seattle, Washington and Ontario, Canada under non-cancelable operating lease agreements. The leases require monthly payments ranging from $4,000 to $7,000 and expire on various dates through February 2027. In addition to minimum rent, the Company is required to pay a proportionate share of operating expenses under these leases.

As of December 31, 2023, the following amounts were presented on SpringBig’s consolidated balance sheets in accordance with the Leasing Standard.

	Year ended December 31,
	2023	2022
Balance Sheet
Assets:
Right of Use Assets - Operating Lease	$340	$750
Liabilities:
Current	99	465
Non-current	225	316
Total Operating Lease Liabilities	$324	$781

	2023	2022
Other information
Operating lease cost	$486	$515
Operating cash flows from operating leases	$520	$318
Disposal of right-of-use assets	$299	$—
Disposal of operating lease liabilities associated with right-of-use assets	$313	$—
Right-of-use assets obtained in exchange for new operating lease liabilities	$412	$150
Weighted-average remaining lease term - operating leases (months)	35.1	20.4
Weighted-average discount rate - operating leases	9%	6%

As of December 31, 2023, the Company’s lease liabilities mature as follows:

			Operating Leases
Fiscal Year:
2024			$124
2025			128
2026			110
2027			9
Total lease payments			371
Less imputed interest			(47)
Present value of lease liabilities			$324

PREPAID EXPENSES AND OTHER CURRENT ASSETS (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

PREPAID EXPENSES AND OTHER CURRENT ASSETS

NOTE 4 – PREPAID EXPENSES AND OTHER CURRENT ASSETS

Prepaid expenses and other current assets consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Prepaid insurance	$109	$379
Other prepaid expenses	390	425
Deposits	89	89
	$588	$893

NOTE 4 – PREPAID EXPENSES AND OTHER CURRENT ASSETS

Prepaid expenses and other current assets consisted of the following (in thousands):

PROPERTY AND EQUIPMENT (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Property and Equipment

Property and equipment consist of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Computer equipment	$448	$416
Furniture & fixtures	176	149
Data warehouse	286	286
Software	197	197
Total cost	1,107	1,048
Less accumulated depreciation and amortization	(782)	(728)
Property and equipment, net	$325	$320

Property and equipment consist of the following (in thousands):

	December 31,
	2023	2022
Computer equipment	$416	$333
Furniture and fixtures	149	15
Data warehouse	286	286
Software	197	197
Total Cost	1,048	831
Less accumulated depreciation and amortization	(728)	(456)
Property and Equipment	$320	$375

PREPAID EXPENSES AND OTHER CURRENT ASSETS (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Prepaid insurance	$109	$379
Other prepaid expenses	390	425
Deposits	89	89
	$588	$893

Prepaid expenses and other current assets consisted of the following (in thousands):

ACCOUNTS RECEIVABLE (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Reverse Recapitalization Business Combination And Asset Acquisition [Abstract]

ACCOUNTS RECEIVABLE

NOTE 3 – ACCOUNTS RECEIVABLE

Accounts receivable, net consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Accounts receivable	$4,005	$3,690
Unbilled receivables	854	853
Total receivables	4,859	4,543
Less allowance for doubtful accounts	(1,648)	(1,595)
Accounts receivable, net	$3,211	$2,948

Bad debt expense was $87,000 and $169,000 for the three months ended March 31, 2024 and 2023, respectively, and is included in general and administrative expenses.

The following table details the activity related to the Company’s allowance for credit losses for the quarter ending March 31, 2024 (in thousands).

			Allowance for credit losses
Outstanding Balance, December 31, 2023			$1,595
Current-period provision (release) for expected credit losses			53
Write-offs charged against the allowance, net of recoveries and other			—
Outstanding Balance, March 31, 2024			$1,648

NOTE 3 – ACCOUNTS RECEIVABLE

Accounts receivable, net consisted of the following (in thousands):

	December 31,
	2023	2022
Accounts receivable	$3,690	$3,639
Unbilled receivables	853	731
Total receivables	4,543	4,370
Less allowance for credit losses	(1,595)	(1,481)
Accounts receivable, net	$2,948	$2,889

Bad debt expense was $1.6 million and $1.5 million for the years ending December 31, 2023 and 2022, respectively.

The following table details the activity related to the Company’s allowance for credit losses for the years ending December 31, 2023 and 2022, respectively (in thousands).

			Allowance for credit losses
Outstanding Balance, January 1, 2023			$1,481
Current-period provision (release) for expected credit losses			1,563
Write-offs charged against the allowance, net of recoveries and other			(1,449)
Outstanding Balance, December 31, 2023			$1,595

SUBSEQUENT EVENTS (FY)	3 Months Ended	12 Months Ended
SUBSEQUENT EVENTS (FY)	Mar. 31, 2024	Dec. 31, 2023
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	NOTE 22 – SUBSEQUENT EVENTS Management has considered subsequent events through May 14, 2024, the date this report was issued, and there were no events that required additional disclosure.	NOTE 23 – SUBSEQUENT EVENTS On January 16, 2024, the Company entered into an agreement with LI Capital Global Opportunities to repurchase the entire outstanding principal of the Secured Convertible Note and cancel the associated warrants. The outstanding principal and accrued interest at the time of repurchase was $5.2 million. SpringBig, using a portion of the proceeds from the 8% Convertible Notes purchased the entire outstanding obligation to LI Capital Global Opportunities for $2.9 million. After the end of the fiscal year, on January 23, 2024, the Company raised $6.4 million through the issuance of 8% Convertible Notes and $1.6 million through the issuance of 12% Term Notes. The net cash proceeds, after transaction expenses, were $7.5 million. The 8% Convertible Notes accrue interest at 8% per annum which is added to the outstanding principal balance annually. The Notes are convertible into common stock at a conversion price of $0.15 per share at the holder's option any time up to the day prior to maturity in January 2026. The 12% Term Notes, due in January 2026, accrue interest payable at 12% per annum in cash semi-annually. The 8% Convertible Notes and 12% Term Notes rank pari passu and are secured by substantially all the assets of the Company. Jeffrey Harris, CEO, Paul Sykes, CFO, and Jon Trauben, Director, agreed to purchase the Convertible Notes and Term Notes for an aggregate amount of $450,000 on the same terms as all other purchasers.

PREPAID EXPENSES AND OTHER CURRENT ASSETS - Summary (FY) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid insurance	$ 109	$ 379	$ 834
Other prepaid expenses	390	425	582
Deposits	89	89	89
Total prepaid expenses and other current assets	$ 588	$ 893	$ 1,505

BUSINESS COMBINATIONS (FY) (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of Reverse Recapitalization

The following table provides a summary of the significant sources and uses of cash related to the closing of the business combination on June 14, 2022, (in thousands):

Amount available after paying TCAC redeeming stockholders			$8,771
Proceeds from convertible notes			10,000
Proceeds from PIPE Financing			6,100
TCAC operating account			264
Gross proceeds available at closing			25,135
Expenses paid at closing			(6,346)
Net cash to Legacy SpringBig at closing			$18,789
Post closing expense (cash paid or accrued for expenses by Legacy SpringBig)			(8,679)
Net cash after closing			$10,110

The following table provides a reconciliation of the common shares related to the business combination transaction:

TCAC non-redeeming shareholders			1,752,388
PIPE Investors			1,341,356
TCAC sponsor shareholders			4,000,000
Legacy SpringBig shareholders			18,196,526
Issued and outstanding			25,290,270

PREPAID EXPENSES AND OTHER CURRENT ASSETS (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Prepaid insurance	$109	$379
Other prepaid expenses	390	425
Deposits	89	89
	$588	$893

Prepaid expenses and other current assets consisted of the following (in thousands):

INCOME TAXES - Deferred Income Tax Assets And Liabilities (FY) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Accrued expenses and other liabilities	$ 771	$ 376
Net operating loss - US Federal	4,848	5,556
Net operating loss - US State	1,020	1,188
Net operating loss - Foreign	711	575
Property and equipment, net	0	8
Operating lease liability	82	198
Research and development	1,974	0
Stock based compensation	525	215
Total gross deferred tax assets	9,931	8,116
Less: valuation allowance	(9,596)	(7,506)
Total deferred tax assets	335	610
Deferred tax liabilities:
Prepaid expenses and other assets	(231)	(420)
Operating lease right of use asset	(79)	(190)
Property and equipment, net	(25)	0
Total deferred tax liabilities	(335)	(610)
Net deferred income tax asset (liability)	$ 0	$ 0

NET INCOME (LOSS) PER SHARE - Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share (Q1) (Details) - shares	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Shares unvested and subject to exercise of stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	13,896	120,431	27,792	144,517
Shares subject to outstanding common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	2,255,034	2,945,020	2,244,102	3,250,236
Shares subject to convertible notes stock conversion
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	695,261	5,111,929	816,667
Shares subject to warrants stock conversion
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	16,000,000	16,586,980	16,586,980	16,586,980
Shares subject to contingent earn out
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	10,500,000	10,500,000	10,500,000	10,500,000
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	2,161,509	1,314,000	2,211,509	725,000

CONSOLIDATED BALANCE SHEETS (FY) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Apr. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 1,668	$ 331		$ 3,546
Accounts receivable, net	3,211	2,948		2,889
Contract assets	255	273		333
Prepaid expenses and other current assets	588	893		1,505
Total current assets	5,722	4,445		8,273
Operating lease assets	3,031	340		750
Property and equipment, net	325	320		375
Convertible note receivable		0		259	$ 250
Total assets	9,078	5,105		9,657
Current liabilities:
Accrued expense and other current liabilities	1,767	1,951		2,554
Short-term cash advances	1,195	1,925		0
Current maturities of long-term debt	0	4,360		5,451
Deferred payroll tax credits	1,751	1,751	$ 1,400	0
Deferred revenue	2	0		291		$ 450
Operating lease liabilities - current	329	99		465
Total current liabilities	7,084	13,551		9,817
Long-term debt, non-current	7,198	0		2,814
Operating lease liabilities - non-current	2,815	225		316
Warrant liabilities	6	3		338
Total liabilities	17,103	13,779		13,285
Commitments and Contingencies
Stockholders' Deficit
Common stock par value $0.0001 per share, 300,000,000 authorized at December 31, 2023; 45,339,762 issued and outstanding as of December 31, 2023; par value $0.0001 per share, 300,000,000 authorized at December 31, 2022; 26,659,711 issued and outstanding as of December 31, 2022	4	4		3
Additional paid-in capital	28,119	27,887		22,701
Accumulated deficit	(36,148)	(36,565)		(26,332)
Total stockholders' deficit	(8,025)	(8,674)	$ (5,615)	(3,628)		$ 4,459
Total liabilities and stockholders' deficit	9,078	5,105		9,657
Nonrelated Party
Current liabilities:
Accounts payable	2,040	2,925		1,056
Related Party
Current liabilities:
Accounts payable	$ 0	$ 540		$ 0

CONSOLIDATED STATEMENTS OF OPERATIONS (FY) - USD ($)	3 Months Ended		12 Months Ended
CONSOLIDATED STATEMENTS OF OPERATIONS (FY) - USD ($)	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Revenues	$ 6,474,000	$ 7,157,000	$ 28,050,000	$ 26,629,000
Cost of revenues	1,794,000	1,350,000	6,486,000	6,701,000
Gross profit	4,680,000	5,807,000	21,564,000	19,928,000
Operating expenses
Selling, servicing and marketing	1,527,000	2,478,000	8,278,000	12,333,000
Technology and software development	1,666,000	2,300,000	8,011,000	11,353,000
General and administrative	1,769,000	2,757,000	13,615,000	12,542,000
Total operating expenses	4,962,000	7,535,000	29,904,000	36,228,000
Loss from operations	(282,000)	(1,728,000)	(8,340,000)	(16,300,000)
Interest income	4,000	10,000	24,000	18,000
Interest expense	(875,000)	(391,000)	(2,247,000)	(949,000)
Gain on note repurchase	1,573,000	0
Change in fair value of warrants	(3,000)	(153,000)	334,000	4,158,000
Income (loss) before income tax	417,000	(2,262,000)	(10,229,000)	(13,073,000)
Income tax expense	0	0	4,000	3,000
Net income (loss)	$ 417,000	$ (2,262,000)	$ (10,233,000)	$ (13,076,000)
Net loss per common share:
Basic (in dollars per share)	$ 0.01	$ (0.08)	$ (0.28)	$ (0.59)
Diluted (in dollars per share)	$ 0.01	$ (0.08)	$ (0.28)	$ (0.59)
Weighted-average common shares outstanding
Weighted-average common shares outstanding - basic (in shares)	45,432,272	26,803,839	36,147,187	22,287,828
Weighted-average common shares outstanding - diluted (in shares)	77,315,056	26,803,839	36,147,187	22,287,828

ACCOUNTS RECEIVABLE - Schedule of Allowance for Credit Loss (FY) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit loss, beginning balance	$ 1,595	$ 1,481
Current-period provision (release) for expected credit losses	53	1,563
Write-offs charged against the allowance, net of recoveries and other	0	(1,449)
Allowance for credit loss, ending balance	$ 1,648	$ 1,595

INCOME TAXES (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Income Tax Disclosure [Abstract]

INCOME TAXES

NOTE 21 – INCOME TAXES

NOTE 22 – INCOME TAXES

U.S. and foreign components of loss from operations before income taxes were as follows (in thousands):

The provision (benefit) for income taxes consist of the following, (in thousands):

	Years Ended December 31,
	2023	2022
Provision (benefit) for income taxes
Current
Federal	$—	$—
State	4	1
International	—	2
	$4	$ 3

The Company’s actual provision (benefit) for income taxes from operations differ from the federal expected income tax provision as follows (in thousands):

	December 31, 2023		December 31, 2022
	Amount	Rate	Amount	Rate
U.S. federal income tax provision (benefit) at statutory rate	$(2,126)	21%	$(2,754)	21%
Increase (decrease) in taxes resulting from:
State income tax expense	4	5%	1	5%
Foreign income and losses taxed at different rates	(28)	1%	(68)	1%
Change in valuation allowance	2,090	(32)%	4,122	(32)%
Non-deductible or non-taxable items	37	5%	(1,302)	5%
Foreign income taxes	—	—%	2	—%
Effect of income tax rate changes on deferred items	27	—%	2	—%
Provision (benefit) for income taxes	$4	—%	$3	—%

	Years Ended December 31,
	2023	2022
Deferred tax assets:
Accrued expenses and other liabilities	$771	$376
Net operating loss - US Federal	4,848	5,556
Net operating loss - US State	1,020	1,188
Net operating loss - Foreign	711	575
Property and equipment, net	—	8
Operating lease liability	82	198
Research and development	1,974	—
Stock based compensation	525	215
Total gross deferred tax assets	$9,931	$8,116
Less: valuation allowance	(9,596)	(7,506)
Total deferred tax assets	335	610
Deferred tax liabilities:
Prepaid expenses and other assets	$(231)	$(420)
Operating lease right of use asset	(79)	(190)
Property and equipment, net	(25)	—
Total deferred tax liabilities	(335)	(610)
Net deferred income tax asset (liability)	$—	$—

CONTRACT ASSETS AND LIABILITIES (FY)

12 Months Ended

Dec. 31, 2023

CONTRACT ASSETS AND LIABILITIES

NOTE 14 – CONTRACT ASSETS AND LIABILITIES

Contract Assets (Deferred Cost)

Contract assets consisted of the following as of (in thousands):

	December 31,
	2023	2022
Deferred sales commissions	$273	$333

Contract liabilities consisted of the following as of (in thousands):

	December 31,
	2023	2022
Deferred retail revenues	$—	$277
Deferred brands revenues	—	14
Contract liabilities	$—	$291

The movement in the contract liabilities during the years ended December 31, 2023 and 2022 comprised the following (in thousands):

	Year ended December 31,
	2023	2022
The movement in the contract liabilities during each period comprised the following:
Contract liabilities at start of the period	$291	$450
Amounts invoiced during the period	—	18,310
Less revenue recognized during the period	(291)	(18,469)
Contract liabilities at end of the period	$—	$291

STOCKHOLDERS EQUITY (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Equity [Abstract]

STOCKHOLDERS' EQUITY

NOTE 18 – STOCKHOLDERS’ EQUITY

Sponsor Escrow Agreement

At the time of the Closing, TCAC Sponsor, LLC, a Delaware limited liability company (“Sponsor”), Tuatara and certain independent members of Tuatara’s board of directors entered into an escrow agreement (“Sponsor Escrow Agreement”), providing that (i) immediately following the Closing, Sponsor and certain of Tuatara’s board of directors’ independent directors shall deposit an aggregate of 1,000,000 shares of our Common Stock (such deposited shares, the “Sponsor Earnout Shares”) into escrow, (ii) the Sponsor Earnout Shares shall be released to the Sponsor if the closing price of our Common Stock equals or exceeds $12.00 per share (as adjusted for share splits, share dividends, reorganizations, and recapitalizations) on any twenty (20) trading days in a thirty (30) trading-day period ending at any time after the Closing Date and before the fifth anniversary of the Closing Date, and (iii) the Sponsor Earnout Shares will be terminated and canceled by us if such condition is not met by the fifth anniversary of the Closing Date.

Contingent and Earnout Shares

The holders of Legacy SpringBig’s common stock and the “engaged option holders” (employees or engaged consultants of Legacy SpringBig who held Legacy SpringBig options at the effective time of the merger and who remains employed or engaged by Legacy SpringBig at the time of such payment of contingent shares) shall be entitled to receive their pro rata portion of such number of shares, fully paid and free and clear of all liens other than applicable federal and state securities law restrictions, as set forth below upon satisfaction of any of the following conditions:

a.	7,000,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $12.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date;

b.	2,250,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $15.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date; and

c.	1,250,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $18.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date.

With the consummation of the business combination, the Company’s authorized capital stock is 350,000,000 shares, consisting of 300,000,000 shares of common stock and 50,000,000 shares of preferred stock, with par value of 0.0001 per share.

NOTE 19 – STOCKHOLDERS’ EQUITY

The Consolidated Statements of Changes in Stockholders' Equity reflect the reverse recapitalization on June 14, 2022, as discussed in Note 9, Business Combinations, to these consolidated financial statements. Because the Company was determined to be the accounting acquirer in the transaction, all periods presented prior to consummation of the transaction reflect the historical activity and balances of Legacy SpringBig, Inc. (other than common stock and potentially issuable shares underlying stock options which have been retroactively restated).

Immediately after giving effect to the business combination, the following equity securities of the SpringBig, were issued and outstanding: (i) 5,752,388 shares of SpringBig, common stock issued to the holders of Tuatara Class A ordinary shares and Tuatara Class B ordinary shares that automatically convert into Tuatara Class A ordinary shares upon the occurrence of the business combination in accordance with Tuatara’s amended and restated memorandum and articles of association as consideration in the business combination (comprised of 1,752,388 Class A ordinary shares after giving effect to the redemptions and the issuance of shares to public shareholders who did not elect to redeem their public shares and 4,000,000 Class B ordinary shares that converted into common stock), (ii) 18,196,526 shares of SpringBig common stock issued to the stockholders of SpringBig as consideration in the business combination, (iii) 10,000,000 warrants to purchase shares of SpringBig common stock issued to holders of the Public Shares upon conversion of warrants to purchase Tuatara Class A ordinary shares in connection with the business combination (each, a “New SpringBig Public Warrant”), (iv) 6,000,000 warrants to purchase shares of SpringBig common stock issued to Sponsor upon conversion of warrants to purchase Tuatara Class A Common Stock, and (v) 1,310,000 shares of SpringBig common stock issued to private investors (the “PIPE Investors”) in the PIPE Financing, plus 31,356 shares paid to certain PIPE Investors pursuant to the Convertible Notes.

Prior to the consummation of the business combination, the capital stock of Legacy SpringBig consisted of Series A, B and Seed preferred stock which was automatically convertible into common stock at the earlier of a $50.0 million initial public offering or vote of 63% of majority of preferred stockholders. The conversation rate of all preferred stock was at a one to one ratio to common stock. The preferred shares of stock were converted to SpringBig common stock at the Closing Date.

With the consummation of the business combination, Legacy SpringBig. issued and outstanding shares were converted into shares of SpringBig common stock as follows:

	Legacy SpringBig	Conversion Rate	SpringBig
Series B Preferred	4,585,202	0.59289	2,718,522
Series A Preferred	5,088,944	0.59289	3,017,184
Series Seed Preferred	6,911,715	0.59289	4,097,887
Common Stock	14,105,371	0.59289	8,362,933
	30,691,232		18,196,526

Sponsor Escrow Agreement

independent directors shall deposit an aggregate of 1,000,000 shares of our Common Stock (such deposited shares, the “Sponsor Earnout Shares”) into escrow, (ii) the Sponsor Earnout Shares shall be released to the Sponsor if the closing price of our Common Stock equals or exceeds $12.00 per share (as adjusted for share splits, share dividends, reorganizations, and recapitalizations) on any twenty (20) trading days in a thirty (30) trading-day period ending at any time after the Closing Date and before the fifth anniversary of the Closing Date, and (iii) the Sponsor Earnout Shares will be terminated and canceled by us if such condition is not met by the fifth anniversary of the Closing Date.

Contingent and Earnout Shares

The holders of Legacy SpringBig’s common stock and the “engaged option holders” (employees or engaged consultants of Legacy SpringBig who held Legacy SpringBig options at the effective time of the business combination and who remains employed or engaged by Legacy SpringBig at the time of such payment of contingent shares) shall be entitled to receive their pro rata portion of such number of shares, fully paid and free and clear of all liens other than applicable federal and state securities law restrictions, as set forth below upon satisfaction of any of the following conditions:

a.	7,000,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $12.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date;

b.	2,250,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $15.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date; and

c.	1,250,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $18.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date.

The entire disclosure for equity.

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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

STOCK BASED COMPENSATION (FY)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

STOCK BASED COMPENSATION

NOTE 14 – STOCK BASED COMPENSATION

In connection with the business combination, the Tuatara shareholders approved the SpringBig Holdings, Inc. 2022 Long-Term Incentive Plan (the “2022 Incentive Plan”), which became effective upon the Closing.

The number of shares of our common stock initially reserved for issuance under the 2022 Incentive Plan was 1,525,175, which equaled the amount of shares of our common stock equal to 5% of the sum of (i) the number of shares of our common stock outstanding as of the Closing and (ii) the number of shares of our common stock underlying stock options issued under the SpringBig, Inc. 2017 Equity Incentive Plan (as amended and restated) (the “Legacy Incentive Plan”) that were outstanding as of the Closing. Shares subject to stock awards granted under the 2022 Incentive Plan that expire or terminate without being exercised in full, or that are paid out in cash rather than in shares, will not reduce the number of shares available for issuance under the 2022 Incentive Plan.

At the annual shareholder meeting on June 13, 2022, the Company shareholders approved an amendment to the 2022 Incentive Plan to add an automatic annual increase in the number of shares authorized for issuance of up to 5% of the number of the Company’s common stock issued and outstanding on December 31 of the immediately preceding calendar year, beginning with the fiscal year ending December 31, 2023; provided that the annual increase with respect to the fiscal year ending December 31, 2023, which is 1,332,986 shares of common stock, took effect on the first business day following the annual shareholder meeting.

The number of shares automatically added to the number of shares authorized for issuance on January 1, 2024, was 2,266,988, being 5% of the number of the Company’s common stock issued and outstanding on December 31, 2023. The total number of shares of common stock authorized for issuance under the 2022 Incentive Plan is 5,125,149 as of March 31, 2024.

Prior to the closing of the merger, Legacy SpringBig maintained an equity incentive plan (the “Legacy Incentive Plan”), which was originally established effective December 1, 2017. SpringBig has not granted any additional awards under the Legacy Incentive Plan following the business combination.

The following table summarizes information on stock options outstanding as of March 31, 2024 under the Legacy Incentive Plan:

	Options Outstanding		Options Vested and Exercisable
	Number of Options	Weighted Average Exercise Price (Per Share)	Number of Options	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price (Per Share)
Outstanding Balance, January 1, 2024	2,271,894	$0.57	2,244,102	4.76	$0.56
Options granted	—
Options exercised	—	$—
Options forfeited	(2,964)	$1.26
Options cancelled	—	$—
Outstanding Balance, March 31, 2024	2,268,930	$0.57	2,255,034	4.57	$0.57

During the three months ended March 31, 2024 and 2023, compensation expense recorded in connection with the Legacy Incentive Plan was $17,000 and $30,000, respectively. These charges are recorded in administrative expense on the condensed consolidated statements of operations.

No options were exercised during the three months ended March 31, 2024. As of March 31, 2024, the intrinsic value of the 2,255,034 options outstanding and exercisable was $0. As of March 31, 2024, the total compensation cost related to non-vested awards not yet recognized was $17,000 with a weighted-average period of.0.25 years over which it is expected to be recognized.

The following table summarizes information on Restricted Stock Units outstanding as of March 31, 2024 under the 2022 Incentive Plan:

	Restricted Stock Units Outstanding
	Number of RSUs	Weighted Average Fair Value (Per Share)	Weighted Average Vesting (Years)
Outstanding Balance, December 31, 2022	725,000	$1.97	2.5
RSUs granted	1,989,000	0.56
RSUs forfeited	(276,836)	1.28
RSUs vested and common stock issued	(225,655)	$1.97
Outstanding Balance, December 31, 2023	2,211,509	$0.80
RSUs forfeited	(50,000)	0.80
Outstanding Balance, March 31, 2024	2,161,509	$0.79	1.9

During the three months ended March 31, 2024 and 2023, compensation expense recorded in connection with the 2023 Incentive Plan was $178,000 and $132,000, respectively. The expense is reported within general and administrative expenses. The remaining expense of approximately $1.1 million will be recognized in future periods through September 2026. The Restricted Stock Units vest one-third on each of the first, second, and third anniversary after issuance.

NOTE 15 – STOCK BASED COMPENSATION

Legacy Incentive Plan

Prior to the closing of the business combination, Legacy SpringBig maintained an equity incentive plan (the “Legacy Incentive Plan”), which was originally established effective December 1, 2017. The Legacy Incentive Plan permitted the grant of incentive stock options, non-qualified stock options, restricted stock awards, and restricted stock unit awards to Legacy SpringBig and its affiliates’ employees, consultants and directors. SpringBig will not grant any additional awards under the Legacy Incentive Plan following the business combination.

The following table summarizes information on stock options outstanding as of December 31, 2023 and 2022 under the Legacy Incentive Plan:

	Options Outstanding		Options Vested and Exercisable
Fixed Options	Number of Options	Weighted Average Exercise Price (Per Share)	Number of Options	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price (Per Share)
Outstanding Balance, January 1, 2022	6,802,437	$0.38	4,628,311	6.79	$0.24
Options exercised	(530,666)	$0.55
Options forfeited	(61,460)	$0.75
Options cancelled	(4,791)	$0.75
Outstanding Balance, June 14, 2022	6,205,520
Conversion ratio	0.5929
SpringBig Holdings options	3,679,171
Options exercised	(135,090)	$0.30
Options forfeited	(149,328)	$1.11	______	___	____
Outstanding Balance, January 1, 2023	3,394,753	$0.57	3,250,236	5.79	$0.54
Options exercised	(727,233)	$0.38
Options forfeited	(25,876)	$0.82
Options cancelled	(369,750)	$0.84
Outstanding Balance, Dec. 31, 2023	2,271,894	$0.57	2,244,102	4.76	$0.56

The intrinsic value of the options exercised during the years ended December 31, 2023 and 2022 was $162,000 and $3,400,000, respectively.

With the consummation of the business combination, all outstanding options were vested with the exception of 192,689 options granted to certain executives of the Company. The cost associated with the early vesting was $0.9 million and is included in administrative expense on the statement of operations for the year ending December 31, 2022.

The Company used the Black-Scholes option-pricing model to value option grants and to determine the related compensation expense. The assumptions used in calculating the fair value of stock-based payment awards represent management’s best estimations. The Company based its expected volatility based on the volatilities of certain publicly traded peer companies.

The risk-free interest rate used for each grant is equal to the U.S. Treasury yield curve in effect at the time of grant for instruments with a similar expected life. The expected term of options granted was determined based on the expected holding period at the time of the grant. GAAP also requires that the Company recognize compensation expense for only the portion of options that are expected to vest.

During the years ended December 31, 2023 and 2022, compensation expense recorded in connection with the Legacy Incentive Plan was $118,000 and $982,000, respectively. As of December 31, 2023, the intrinsic value of the remaining options was $0 and the remaining expense to be recognized under the Legacy Incentive Plan was $35,000. These charges are recorded in administrative expense on the consolidated statements of operations.

2022 Incentive Plan

At the Special Meeting, in connection with the business combination, the Tuatara shareholders approved the SpringBig Holdings, Inc. 2022 Long-Term Incentive Plan (the “2022 Incentive Plan”), which became effective upon the Closing.

The number of shares of our common stock initially reserved for issuance under the 2022 Incentive Plan was 1,525,175, which equaled the amount of shares of our common stock equal to 5% of the sum of (i) the number of shares of our common stock outstanding as of the Closing and (ii) the number of shares of our common stock underlying stock options issued under the SpringBig, Inc. 2017 Equity Incentive Plan (as amended and restated) (the “Legacy Incentive Plan”) that were outstanding as of the Closing. An additional 1,332,986 shares, equal to 5% of the number of shares of common stock outstanding at December 31, 2022, were reserved for issuance following approval by shareholders at the annual shareholder meeting on June 13, 2022. Shares subject to stock awards granted under the 2022 Incentive Plan that expire or terminate without being exercised in full, or that are paid out in cash rather than in shares, will not reduce the number of shares available for issuance under the 2022 Incentive Plan.

The following table summarizes information on Restricted Stock Units outstanding as of December 31, 2023 under the 2022 Incentive Plan:

	Restricted Stock Units Outstanding
	Number of RSUs	Weighted Average Fair Value (Per Share)	Weighted Average Vesting (Years)
Outstanding Balance, January 1, 2022	—
RSUs granted	761,500	$1.97
RSUs forfeited	(36,500)	$1.97
Outstanding Balance, January 1, 2023	725,000	$1.97	2.5
RSUs granted	1,989,000	$0.56
RSUs forfeited	(276,836)	$1.28
RSUs vested and common stock issued	(225,655)	$1.97
Outstanding Balance, December 31, 2023	2,211,509	$0.80	2.2

During the years ended December 31, 2023 and 2022, compensation expense recorded in connection with the 2022 Incentive Plan was $704,000 and $246,000, respectively. These charges are recorded in administrative expense on the consolidated statements of operations.

The remaining expense of approximately $1,336,000 will be recognized in future periods through June 2026. The Restricted Stock Units vest one-third on each of the first, second, and third anniversary after issuance.

CONVERTIBLE NOTE RECEIVABLE (FY)	3 Months Ended	12 Months Ended
CONVERTIBLE NOTE RECEIVABLE (FY)	Mar. 31, 2024	Dec. 31, 2023
Receivables [Abstract]
CONVERTIBLE NOTE RECEIVABLE	NOTE 6 – CONVERTIBLE NOTE RECEIVABLE In April 2022, the Company purchased $250,000 in aggregate principal amount of convertible promissory note due April 1, 2026 (the “Convertible Note Receivable”). The Convertible Note Receivable accrued interest at the rate of 5% per annum on the principal amount of the Convertible Note Receivable. The Company determined that the fair value of the Convertible Note was $0 at December 31, 2023. The loss of $272,000, including $22,000 of accrued interest income, was recorded in interest expense on the Company’s condensed consolidated statements of operations for the year ended December 31, 2023.	NOTE 6 – CONVERTIBLE NOTE RECEIVABLE In April 2022, the Company purchased $250,000 in aggregate principal amount of convertible promissory note due April 1, 2026 (the “Convertible Note Receivable”). The Convertible Note Receivable accrued interest at the rate of 5% per annum on the principal amount of the Convertible Note Receivable. The Company determined that the fair value of the Convertible Note was $0 at December 31, 2023. The loss of $272,000, including $22,000 of accrued interest income, was recorded in general and administrative expenses on the Company’s consolidated statements of operations.

CONTRACT ASSETS AND LIABILITIES (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Contract with Customer, Contract Asset, Contract Liability, and Receivable

Contract assets consisted of the following as of (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Deferred sales commissions	$255	$273

The movement in the contract assets during the three months ended March 31, 2024 and the year ended December 31, 2023, comprised the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Contract assets at start of the period	$273	$333
Expense deferred during the period	36	165
(Less) amounts expensed during the period	(54)	(225)
Contract assets at end of the period	$255	$273

Contract assets consisted of the following as of (in thousands):

	December 31,
	2023	2022
Deferred sales commissions	$273	$333

Contract liabilities consisted of the following as of (in thousands):

	December 31,
	2023	2022
Deferred retail revenues	$—	$277
Deferred brands revenues	—	14
Contract liabilities	$—	$291

The movement in the contract liabilities during the years ended December 31, 2023 and 2022 comprised the following (in thousands):

	Year ended December 31,
	2023	2022
The movement in the contract liabilities during each period comprised the following:
Contract liabilities at start of the period	$291	$450
Amounts invoiced during the period	—	18,310
Less revenue recognized during the period	(291)	(18,469)
Contract liabilities at end of the period	$—	$291

NET LOSS PER SHARE (FY) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Reconciliation of Actual Basic and Diluted Earnings Per Share

The following table reconciles actual basic and diluted income (loss) per share for the three months ended March 31, 2024 and 2023, respectively (in thousands, except share and per share data).

	Three Months Ended March 31,
	2024	2023
Numerator:
Net income (loss) for basic net income (loss) calculation	$417	$(2,262)
Effect of dilutive securities:
Interest expense on Convertible Notes	85	—
Net income (loss) for diluted net income (loss) calculation	$502	$(2,262)

	Three Months Ended March 31,
	2024	2023
Denominator
Denominator for basic net income (loss) per share, weighted average	45,432,272	26,803,839
Effect of dilutive securities:
Convertible notes stock conversion, weighted average as converted	31,882,784	—
Denominator for diluted net income per share	77,315,056	26,803,839
Net income (loss) per common share
Basic	$0.01	$(0.08)
Diluted	$0.01	$(0.08)

The following table reconciles actual basic and diluted earnings per share for the years ended December 31, 2023 and 2022, respectively (in thousands, except share and per share data).

	Years Ended December 31,
	2023	2022
Loss per share:
Numerator:
Net loss	$(10,233)	$(13,076)
Denominator
Weighted-average common shares outstanding
Basic and diluted	36,147,187	22,287,828
Net loss per common share
Basic and diluted	$(0.28)	$(0.59)

Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share

	Three Months Ended March 31,
	2024	2023
Shares unvested and subject to exercise of stock options	13,896	120,431
Shares subject to outstanding common stock options	2,255,034	2,945,020
Shares subject to convertible notes stock conversion	—	695,261
Shares subject to warrants stock conversion	16,000,000	16,586,980
Shares subject to contingent earn out	10,500,000	10,500,000
Restricted stock units	2,161,509	1,314,000

The anti-dilutive securities excluded from the weighted-average shares used to calculate the diluted net loss per common share for the years ended December 31, 2023 and 2022 were as follows:

	Years Ended December 31,
	2023	2022
Shares unvested and subject to exercise of stock options	27,792	144,517
Shares subject to outstanding common stock options	2,244,102	3,250,236
Shares subject to convertible notes stock conversion	5,111,929	816,667
Shares subject to warrants stock conversion	16,586,980	16,586,980
Shares subject to contingent earn out	10,500,000	10,500,000
Restricted stock units	2,211,509	725,000

INCOME TAXES - Effective Income Tax Rate Reconciliation (FY) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Amount
U.S. federal income tax provision (benefit) at statutory rate			$ (2,126)	$ (2,754)
State income tax expense			4	1
Foreign income and losses taxed at different rates			(28)	(68)
Change in valuation allowance			2,090	4,122
Non-deductible or non-taxable items			37	(1,302)
Foreign income taxes			0	2
Effect of income tax rate changes on deferred items			27	2
Income tax expense	$ 0	$ 0	$ 4	$ 3
Rate
U.S. federal income tax provision (benefit) at statutory rate			21.00%	21.00%
State income tax expense			5.00%	5.00%
Foreign income and losses taxed at different rates			1.00%	1.00%
Change in valuation allowance			(32.00%)	(32.00%)
Non-deductible or non-taxable items			5.00%	5.00%
Foreign income taxes			0.00%	0.00%
Effect of income tax rate changes on deferred items			0.00%	0.00%
Provision (benefit) for income taxes			0.00%	0.00%

CONTRACT ASSETS AND LIABILITIES (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

CONTRACT ASSETS AND LIABILITIES

NOTE 12 – REVENUE RECOGNITION

The following table represents our revenues disaggregated by type (in thousands):

	Three Months Ended March 31,
	2024	2023
Revenue
Brand revenue	$59	$295
Retail revenue	6,415	6,862
Total revenue	$6,474	$7,157

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Three Months Ended March 31,
	2024	2023
Brand revenue
United States	$59	$294
Canada	—	1
Retail revenue
United States	6,273	6,663
Canada	142	199
	$6,474	$7,157

NOTE 13 – CONTRACT ASSETS AND LIABILITIES

Contract assets consisted of the following as of (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Deferred sales commissions	$255	$273

The movement in the contract assets during the three months ended March 31, 2024 and the year ended December 31, 2023, comprised the following (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
Contract assets at start of the period	$273	$333
Expense deferred during the period	36	165
(Less) amounts expensed during the period	(54)	(225)
Contract assets at end of the period	$255	$273

NOTE 13 – REVENUE RECOGNITION

The following table represents our revenues disaggregated by type (in thousands):

	Year ended December 31,
	2023	2022
Revenue
Brand revenue	$901	$940
Retail revenue	27,149	25,689
Total Revenue	$28,050	$26,629

Geographic Information

Revenue by geographical region consist of the following (in thousands):

	Year ended December 31,
	2023	2022
Brand revenue
United States	$889	$936
Canada	12	4
Retail revenue
United States	26,372	25,075
Canada	777	614
	$28,050	$26,629

Document and Entity Information	12 Months Ended
Document and Entity Information	Dec. 31, 2023
Cover [Abstract]
Document Type	S-1
Amendment Flag	false
Entity Registrant Name	SpringBig Holdings, Inc.
Entity Central Index Key	0001801602
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false

PREPAID EXPENSES AND OTHER CURRENT ASSETS - Schedule of Prepaid Expenses and Other Current Assets (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid insurance	$ 109	$ 379	$ 834
Other prepaid expenses	390	425	582
Deposits	89	89	89
Total prepaid expenses and other current assets	$ 588	$ 893	$ 1,505

SENIOR SECURED CONVERTIBLE NOTES (FY)	12 Months Ended
SENIOR SECURED CONVERTIBLE NOTES (FY)	Dec. 31, 2023
Debt Disclosure [Abstract]
SENIOR SECURED CONVERTIBLE NOTES	NOTE 11 – SENIOR SECURED CONVERTIBLE NOTES In connection with the business combination, on June 14, 2022, the Company issued $11.0 million in aggregate principal amount of Senior Secured Original Issue Discount Convertible Note, due June 14, 2024 (the “Secured Convertible Notes”), issued at a discount of $1.0 million, with proceeds of $10.0 million received on the Closing Date. The Secured Convertible Notes, as originally issued, accrue interest at the rate of 6.0% per annum which, along with equal principal payments through June 2024, are due in cash in arrears beginning six months after the notes’ issuance. The Company may, at its option, satisfy each principal payment either in cash or, if certain conditions set forth in the Secured Convertible Notes are met, by issuing a number of shares of common stock equal to the amount due on such date divided by the lower of (i) the number of shares determined based on at a rate of $12.00 per share or (ii) 93% of the volume-weighted average price prior to such monthly payment date. A warrant representing 586,890 shares of common stock of the Company (the “Convertible Warrant”) with a fair value of $839,000 was also issued in a private placement with the purchaser party thereto. To determine the fair value of the Convertible Warrant, the Company performed a Black-Scholes calculation as of June 14, 2022 using a stock price of $4.28, a strike price of $12.00, a risk free rate of 3.61%, annualized volatilty of 65%, and a time to maturity of five years. The Convertible Warrant is exercisable for shares of the Company’s common stock at an exercise price of $12.00 per share, subject to certain anti-dilution adjustments. The Convertible Warrants are classified as equity on SpringBig’s consolidated balance sheets. The Secured Convertible Notes are secured against substantially all the assets of the Company and each material subsidiary, including Legacy SpringBig. The Secured Convertible Notes include restrictive covenants that, among other things, limit the ability of the Company to incur additional indebtedness and guarantee indebtedness; incur liens or allow mortgages or other encumbrances; prepay, redeem, or repurchase certain other debt; pay dividends or make other distributions or repurchase or redeem our capital stock; sell assets or enter into or effect certain other transactions (including a reorganization, consolidation, dissolution or similar transaction or selling, leasing, licensing, transferring or otherwise disposing of assets of the Company or its subsidiaries); issue additional equity (outside of the equity issuances under our equity compensation plan and other limited exceptions); enter into variable rate transactions; adopt certain amendments to our governing documents, among other restrictions; and maintain the Nasdaq minimum bid price requirement under Nasdaq Listing Rule 5450(a)(1). The Notes also contain customary events of default. On May 24, 2023 and May 25, 2023, the Company entered into amendments to the Secured Convertible Notes which provide, among other provisions, amended repayment terms, including extending the term to March 2025, and an adjustment in the conversion share price to $1.00, and amended the warrant exercise price to $1.00. The Company accounted for the amendments as a debt modification pursuant to ASC 470-50-40-10. The impact to the financial statements of the debt modification was not significant. As noted in Note 1, on September 5, 2023, Nasdaq filed a Form 25 Notification of Delisting with respect to Springbig’s common stock and public warrants with the SEC. While delisting is an event of default under the terms of the Secured Convertible Notes, the holder has not exercised its right to accelerate payment. The holder is entitled to certain remedies upon an event of default, including but not limited to, conversion at the mandatory default amount of 115% of the principal amount of the Secured Convertible Notes at the default conversion price of 0.80 times the market price of our common stock. As a result of the default, the debt has been classified as current on the Company’s consolidated balance sheet. At December 31, 2023, the outstanding principal of the Secured Convertible Notes was $5.1 million with a carrying value of $4.4 million, net of discount of $0.7 million. At December 31, 2022, the outstanding principal of the Secured Convertible Notes was $9.8 million with a carrying value of $8.3 million, net of discount of $1.5 million. The Company recorded $402,000 and $356,000 of interest expense in connection with the Senior Secured Convertible Notes for the years ended December 31, 2023 and 2022, respectively. As disclosed in Note 23, on January 16, 2024, the Company and the noteholder executed an agreement for the Company to repurchase the outstanding note and associated warrants, and on January 23, 2024, the note and associated warrants were repurchased for $2.9 million.

BENEFIT PLAN (Q1) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
BENEFIT PLAN (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Postemployment Benefits [Abstract]
Company matching contributions	$ 96	$ 158	$ 529	$ 502

FAIR VALUE MEASUREMENTS (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Schedule of Fair Value, Liabilities Measured on Recurring Basis

The balances of the Company’s liabilities measured at fair value on a recurring basis as of March 31, 2024, are as follows (in thousands):

	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	6	—	—	6
	$6	$—	$—	$6

The balances of the Company’s liabilities measured at fair value on a recurring basis as of December 31, 2023, are as follows (in thousands):

	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	3	—	—	3
	$3	$—	$—	$3

The balances of the Company’s liabilities measured at fair value on a recurring basis as of December 31, 2023 and 2022, are as follows (in thousands):

For the year ended December 31, 2022	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	338	—	—	338
	$338	$—	$—	$338

For the year ended December 31, 2023	Level 1	Level 2	Level 3	Total Fair Value
Liabilities:
Public warrants	3	—	—	3
	$3	$—	$—	$3

Schedule of Changes in Fair Value

The following tables provides a roll-forward in the changes in fair value in the public warrants for the three months ended March 31, 2024 (in thousands):

Warrants
Balance, January 1, 2024			$3
Change in fair value			3
Balance, March 31, 2024			$6
Changes in fair value included in earnings for the period relating to liabilities held at March 31, 2024			$3

Warrants
Balance, January 1, 2022			$—
Assumed in business combination at fair value			$4,496
Change in value			$(4,158)
Balance, December 31, 2022			$338
Changes in fair value included in earnings for the period relating to liabilities held at December 31, 2022			$(4,158)

Balance, January 1, 2023			$338
Change in fair value			(335)
Balance, December 31, 2023			$3
Changes in fair value included in earnings for the period relating to liabilities held at December 31, 2023			$(335)

CONSOLIDATED STATEMENTS OF CASH FLOWS (FY) - USD ($)

12 Months Ended

Dec. 31, 2023

Dec. 31, 2022

Cash flows from operating activities:

Adjustments to reconcile net loss to net cash used in operating activities:

$ (10,233,000)

$ (13,076,000)

Depreciation and amortization

272,000

259,000

Discount amortization on convertible notes

783,000

304,000

Stock-based compensation expense

821,000

1,226,000

Amortization of operating lease right of use assets

409,000

318,000

Bad debt expense

1,563,000

1,474,000

Convertible note impairment

259,000

Abandoned software implementation assets

134,000

Accrued interest on convertible notes

68,000

26,000

Change in fair value of warrants

(334,000)

(4,158,000)

Changes in operating assets and liabilities:

Accounts receivable

(1,621,000)

(1,317,000)

Prepaid expenses and other current assets

613,000

(578,000)

Contract assets

60,000

31,000

Accounts payable and other liabilities

2,228,000

1,450,000

Operating lease liabilities

(458,000)

(318,000)

Deferred payroll tax credits

1,751,000

Deferred revenue

(291,000)

(159,000)

Net cash provided by (used in) operating activities

(3,976,000)

(14,518,000)

Cash flows from investing activities:

Purchase of convertible note

(259,000)

Purchases of property and equipment

(351,000)

(154,000)

Net cash used in investing activities

(351,000)

(413,000)

Cash flows from financing activities:

Business combination, net of transaction cost

10,110,000

Proceeds from short-term cash advance

2,467,000

Repayment of short-term cash advance

(542,000)

Proceeds from related party payable

350,000

Related party repayments

(522,000)

Proceeds from convertible notes

7,000,000

Repayment of convertible notes

(3,238,000)

(1,000,000)

Proceeds from the issuance of common stock

2,661,000

Cost of equity issuance

(338,000)

Proceeds from exercise of stock options

274,000

140,000

Net cash provided by (used in) financing activities

1,112,000

16,250,000

Net increase (decrease) in cash and cash equivalents

(3,215,000)

1,319,000

Cash and cash equivalents at beginning of period

3,546,000

2,227,000

Cash and cash equivalents at end of period

331,000

3,546,000

Supplemental cash flows disclosures

Income taxes paid

3,000

2,000

Interest paid

1,432,000

330,000

Supplemental disclosure of non cash activities

Conversion of convertible notes and interest into common stock

7,305,000

Warrants assumed in business combination at estimated fair value

4,496,000

Conversion of L1 Notes into common stock

1,450,000

200,000

Right of use assets obtained in exchange for lease obligations - operating leases

412,000

150,000

712,000

Common stock issued for services rendered

56,000

^[1]

Settlement of litigation through issuance of common stock

$ 263,000

$ 0

[1]	Common shares issued in exchange for services rendered

REVENUE RECOGNITION - Narrative (FY) (Details)	3 Months Ended		12 Months Ended
REVENUE RECOGNITION - Narrative (FY) (Details)	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Geographic Concentration Risk \| Revenue from Contract with Customer Benchmark \| United States
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	98.00%	97.00%	97.00%	98.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

ACCOUNTS RECEIVABLE - Narratives (FY) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Receivables [Abstract]
Bad debt expense	$ 87	$ 169	$ 1,563	$ 1,474

LONG-TERM DEBT - Narrative (Q1) (Details) - USD ($)	3 Months Ended		12 Months Ended
LONG-TERM DEBT - Narrative (Q1) (Details) - USD ($)	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Jan. 23, 2024
Debt Instrument [Line Items]
Interest expense	$ 875,000	$ 391,000	$ 2,247,000	$ 949,000
Term Note And 8.00% Convertible Note \| Secured Debt
Debt Instrument [Line Items]
Interest expense	$ 233,000
12% Secured Term Notes, due January 23, 2026 \| Secured Debt
Debt Instrument [Line Items]
Aggregate principal amount					$ 1,600,000
Interest rate (as percent)					12.00%
8% Secured Convertible Notes, due January 23, 2026 \| Convertible Debt
Debt Instrument [Line Items]
Aggregate principal amount					$ 6,400,000
Interest rate (as percent)					8.00%
Conversion price (dollars per share)					$ 0.15

DESCRIPTION OF BUSINESS (FY) (Details) $ in Thousands		1 Months Ended	3 Months Ended		12 Months Ended
DESCRIPTION OF BUSINESS (FY) (Details) $ in Thousands	Jun. 14, 2022 USD ($)	Feb. 28, 2022 USD ($)	Mar. 31, 2024 USD ($) subsidiary	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) subsidiary	Dec. 31, 2022 USD ($)
Business Acquisition [Line Items]
Number of subsidiaries \| subsidiary			1		1
Recapitalization exchange ratio	0.59289
Net proceeds from reverse recapitalization transaction	$ 18,789
Gross proceeds available at closing	25,135
Proceeds from convertible notes		$ 7,000	$ 6,400	$ 0	$ 0	$ 7,000
Amount available after paying TCAC redeeming stockholders	8,771
Proceeds from PIPE Financing	6,100
Payment of cash and noncash expenses	8,679
Net cash after closing	10,110
Convertible Notes Payable
Business Acquisition [Line Items]
Proceeds from convertible notes	$ 10,000
Convertible Notes Payable \| 15.00% Convertible Notes
Business Acquisition [Line Items]
Interest rate	15.00%	15.00%

RELATED PARTY TRANSACTIONS (FY)	3 Months Ended	12 Months Ended
RELATED PARTY TRANSACTIONS (FY)	Mar. 31, 2024	Dec. 31, 2023
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	NOTE 8 – RELATED PARTY TRANSACTIONS The Company incurred software development and information technology related costs to a vendor related through common ownership to a major stockholder of approximately $2,000 for the three months ended March 31, 2024, and $4,000 for the three months ended March 31, 2023, respectively, and the related expense is recorded to technology and software development costs on the condensed consolidated statement of operations. Amounts due to this related party were $2,000 and $2,000 at March 31, 2024 and December 31, 2023, respectively. The $540,000 related party payable at December 31, 2023, was repaid in January 2024, following completion of the issuance of $6.4 million aggregate principal amount of 8% Secured Convertible Notes and $1.6 million aggregate principal amount of 12% Secured Term Notes. Jeffrey Harris, CEO, and Paul Sykes, CFO, both participated in the debt financing transaction completed on January 23, 2024. Jeffrey Harris purchased $320,000 8% Secured Convertible Notes, due 2026, and $80,000 12% Secured Term Notes, due 2026. Paul Sykes purchased $25,000 8% Secured Convertible Notes, due 2026, and $6,250 12% Secured Term Notes, due 2026. There are two members of the board of directors at March 31, 2024, who are related parties to investors in the debt financing transaction completed on January 23, 2024. In aggregate these investors purchased $5.2 million 12% Secured Convertible Notes and $1.3 million 8% Secured Term Notes.	NOTE 8 – RELATED PARTY TRANSACTIONS The Company incurred software development and information technology related costs to a vendor related through common ownership to a major stockholder of approximately $13,000 and $153,000 for the years ended December 31, 2023 and 2022, respectively. These amounts are included in technology and software development expenses. At December 31, 2023 and 2022, the Company has recorded $2,000 and $3,000, respectively, in accounts payable related to this related party vendor. During 2023, SpringBig’s CEO, Jeffrey Harris, advanced and paid certain expenses on behalf of the Company of approximately $1.0 million for use in operations. As of December 31, 2023, the Company repaid Mr. Harris approximately $0.5 million. The remaining $0.5 million is included in current liabilities on the Company’s consolidated balance sheets.

BUSINESS COMBINATIONS - Schedule Of Proceeds From Reverse Recapitalization (FY) (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 14, 2022	Feb. 28, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Reverse Recapitalization [Line Items]
Amount available after paying TCAC redeeming stockholders	$ 8,771
Proceeds from convertible notes		$ 7,000	$ 6,400	$ 0	$ 0	$ 7,000
Proceeds from PIPE Financing	6,100
TCAC operating account	264
Gross proceeds available at closing	25,135
Expenses paid at closing	(6,346)
Net cash to Legacy SpringBig at closing	18,789
Post closing expense (cash paid or accrued for expenses by Legacy SpringBig)	(8,679)
Net cash after closing	10,110
Convertible Notes Payable
Schedule Of Reverse Recapitalization [Line Items]
Proceeds from convertible notes	$ 10,000

LEASES - Schedule of Lease Cost and Other Information (Q1) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease cost	$ 160,000	$ 133,000	$ 486,000	$ 515,000
Operating cash flows paid to operating leases	31,000	126,000	520,000	318,000
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 2,781,000	$ 0	$ 412,000	$ 150,000
Weighted-average remaining lease term - operating leases (months)	89 years 10 months 24 days	17 years 10 months 24 days	35 years 1 month 6 days	20 years 4 months 24 days
Weighted-average discount rate - operating leases	9.05%	5.67%	9.00%	6.00%

STOCKHOLDERS EQUITY - Narrative (FY) (Details) $ / shares in Units, $ in Millions	Jun. 14, 2022 USD ($) day $ / shares shares	Mar. 31, 2024 $ / shares shares	Dec. 31, 2023 $ / shares shares	Mar. 31, 2023 shares	Dec. 31, 2022 $ / shares shares	Jun. 15, 2022 shares	Jun. 13, 2022 shares
Class of Stock [Line Items]
Common stock, shares, issued (in shares)	25,290,270	45,594,864	45,339,762	26,940,841	26,659,711
Common stock, shares, outstanding (in shares)	25,290,270	45,594,864	45,339,762	26,940,841	26,659,711
Convertible amount of initial public offering \| $	$ 50.0
Percent of total convertible votes	63.00%
Conversation rate of preferred stock	1
Sponsor earnout shares (in shares)	1,000,000
Stock price trigger (in dollars per share) \| $ / shares	$ 12
Number of trading days \| day	20
Number of consecutive trading days \| day	30
Capital stock authorized (in shares)	350,000,000
Common stock, shares authorized (in shares)	300,000,000	300,000,000	300,000,000		300,000,000
Preferred stock, shares authorized (in shares)	50,000,000
Common stock, par or stated value per share (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001	$ 0.0001		$ 0.0001
Preferred stock, par or stated value per share (in dollars per share) \| $ / shares	$ 0.0001
Private Placement Warrant
Class of Stock [Line Items]
Warrants outstanding (in shares)	6,000,000
TCAC shareholders
Class of Stock [Line Items]
Common stock, shares, issued (in shares)						5,752,388
Common stock, shares, outstanding (in shares)						5,752,388
TCAC non-redeeming shareholders
Class of Stock [Line Items]
Issue of common stock (in shares)	1,752,388
TCAC initial shareholders
Class of Stock [Line Items]
Issue of common stock (in shares)	4,000,000
Legacy SpringBig shareholders
Class of Stock [Line Items]
Common stock, shares, issued (in shares)	8,362,933
Common stock, shares, outstanding (in shares)	8,362,933
Issue of common stock (in shares)	18,196,526
PIPE Investors without convertible securities holdings
Class of Stock [Line Items]
Issue of common stock (in shares)	1,310,000
PIPE Investors holding convertible notes
Class of Stock [Line Items]
Issue of common stock (in shares)	31,356
Contingent And Earnout Shares, Scenario One
Class of Stock [Line Items]
Contingent and earnout shares, to be issued (in shares)	7,000,000
Contingent and earnout shares, stock price threshold (in dollars per share) \| $ / shares	$ 12
Contingent and earnout shares, stock price threshold, triggering event period \| day	20
Contingent and earnout shares, stock price threshold, trading days period \| day	30
Contingent and earnout shares, stock price threshold, contingency period	60 months
Contingent And Earnout Shares, Scenario Two
Class of Stock [Line Items]
Contingent and earnout shares, to be issued (in shares)	2,250,000
Contingent and earnout shares, stock price threshold (in dollars per share) \| $ / shares	$ 15
Contingent and earnout shares, stock price threshold, triggering event period \| day	20
Contingent and earnout shares, stock price threshold, trading days period \| day	30
Contingent and earnout shares, stock price threshold, contingency period	60 months
Contingent And Earnout Shares, Scenario Three
Class of Stock [Line Items]
Contingent and earnout shares, to be issued (in shares)	1,250,000
Contingent and earnout shares, stock price threshold (in dollars per share) \| $ / shares	$ 18
Contingent and earnout shares, stock price threshold, triggering event period \| day	20
Contingent and earnout shares, stock price threshold, trading days period \| day	30
Contingent and earnout shares, stock price threshold, contingency period	60 months
Class A common stock \| Redeemable Warrants
Class of Stock [Line Items]
Warrants outstanding (in shares)							10,000,000

INCOME TAXES - U.S. and Foreign Components of Income (loss) (FY) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
U.S.	$ (9,717)	$ (11,828)
Foreign	(516)	(1,248)
Loss from operations	$ (10,233)	$ (13,076)

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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Schedule of Long-Term Debt Instruments

LONG-TERM DEBT (Q1) (Tables)

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

The table below presents the components of outstanding debt (in thousands):

	March 31, 2024	December 31, 2023
	(unaudited)	(audited)
12% Secured Term Notes, due January 23, 2026	$1,600	$—
8% Secured Convertible Notes, due January 23, 2026	6,400	—
	$8,000	$—
Less: Deferred financing fees, net	(802)	—
	$7,198	$—

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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ACCOUNTS RECEIVABLE - Schedule of Accounts Receivable (Q1) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Receivables [Abstract]
Accounts receivable	$ 4,005	$ 3,690	$ 3,639
Unbilled receivables	854	853	731
Total receivables	4,859	4,543	4,370
Less allowance for doubtful accounts	(1,648)	(1,595)	(1,481)
Accounts receivable, net	$ 3,211	$ 2,948	$ 2,889

INCOME TAXES - Provision (Benefit) For Income Taxes (FY) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Current
Federal	$ 0	$ 0
State	4	1
International	0	2
Provision (benefit) for income taxes	$ 4	$ 3

STOCK BASED COMPENSATION (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

STOCK BASED COMPENSATION

NOTE 14 – STOCK BASED COMPENSATION

The following table summarizes information on stock options outstanding as of March 31, 2024 under the Legacy Incentive Plan:

	Options Outstanding		Options Vested and Exercisable
	Number of Options	Weighted Average Exercise Price (Per Share)	Number of Options	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price (Per Share)
Outstanding Balance, January 1, 2024	2,271,894	$0.57	2,244,102	4.76	$0.56
Options granted	—
Options exercised	—	$—
Options forfeited	(2,964)	$1.26
Options cancelled	—	$—
Outstanding Balance, March 31, 2024	2,268,930	$0.57	2,255,034	4.57	$0.57

The following table summarizes information on Restricted Stock Units outstanding as of March 31, 2024 under the 2022 Incentive Plan:

	Restricted Stock Units Outstanding
	Number of RSUs	Weighted Average Fair Value (Per Share)	Weighted Average Vesting (Years)
Outstanding Balance, December 31, 2022	725,000	$1.97	2.5
RSUs granted	1,989,000	0.56
RSUs forfeited	(276,836)	1.28
RSUs vested and common stock issued	(225,655)	$1.97
Outstanding Balance, December 31, 2023	2,211,509	$0.80
RSUs forfeited	(50,000)	0.80
Outstanding Balance, March 31, 2024	2,161,509	$0.79	1.9

NOTE 15 – STOCK BASED COMPENSATION

Legacy Incentive Plan

The following table summarizes information on stock options outstanding as of December 31, 2023 and 2022 under the Legacy Incentive Plan:

	Options Outstanding		Options Vested and Exercisable
Fixed Options	Number of Options	Weighted Average Exercise Price (Per Share)	Number of Options	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price (Per Share)
Outstanding Balance, January 1, 2022	6,802,437	$0.38	4,628,311	6.79	$0.24
Options exercised	(530,666)	$0.55
Options forfeited	(61,460)	$0.75
Options cancelled	(4,791)	$0.75
Outstanding Balance, June 14, 2022	6,205,520
Conversion ratio	0.5929
SpringBig Holdings options	3,679,171
Options exercised	(135,090)	$0.30
Options forfeited	(149,328)	$1.11	______	___	____
Outstanding Balance, January 1, 2023	3,394,753	$0.57	3,250,236	5.79	$0.54
Options exercised	(727,233)	$0.38
Options forfeited	(25,876)	$0.82
Options cancelled	(369,750)	$0.84
Outstanding Balance, Dec. 31, 2023	2,271,894	$0.57	2,244,102	4.76	$0.56

The intrinsic value of the options exercised during the years ended December 31, 2023 and 2022 was $162,000 and $3,400,000, respectively.

2022 Incentive Plan

The number of shares of our common stock initially reserved for issuance under the 2022 Incentive Plan was 1,525,175, which equaled the amount of shares of our common stock equal to 5% of the sum of (i) the number of shares of our common stock outstanding as of the Closing and (ii) the number of shares of our common stock underlying stock options issued under the SpringBig, Inc. 2017 Equity Incentive Plan (as amended and restated) (the “Legacy Incentive Plan”) that were outstanding as of the Closing. An additional 1,332,986 shares, equal to 5% of the number of shares of common stock outstanding at December 31, 2022, were reserved for issuance following approval by shareholders at the annual shareholder meeting on June 13, 2022. Shares subject to stock awards granted under the 2022 Incentive Plan that expire or terminate without being exercised in full, or that are paid out in cash rather than in shares, will not reduce the number of shares available for issuance under the 2022 Incentive Plan.

The following table summarizes information on Restricted Stock Units outstanding as of December 31, 2023 under the 2022 Incentive Plan:

	Restricted Stock Units Outstanding
	Number of RSUs	Weighted Average Fair Value (Per Share)	Weighted Average Vesting (Years)
Outstanding Balance, January 1, 2022	—
RSUs granted	761,500	$1.97
RSUs forfeited	(36,500)	$1.97
Outstanding Balance, January 1, 2023	725,000	$1.97	2.5
RSUs granted	1,989,000	$0.56
RSUs forfeited	(276,836)	$1.28
RSUs vested and common stock issued	(225,655)	$1.97
Outstanding Balance, December 31, 2023	2,211,509	$0.80	2.2

CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) (Q1) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Revenues	$ 6,474,000	$ 7,157,000	$ 28,050,000	$ 26,629,000
Cost of revenues	1,794,000	1,350,000	6,486,000	6,701,000
Gross profit	4,680,000	5,807,000	21,564,000	19,928,000
Operating expenses
Selling, servicing and marketing	1,527,000	2,478,000	8,278,000	12,333,000
Technology and software development	1,666,000	2,300,000	8,011,000	11,353,000
General and administrative	1,769,000	2,757,000	13,615,000	12,542,000
Total operating expenses	4,962,000	7,535,000	29,904,000	36,228,000
Loss from operations	(282,000)	(1,728,000)	(8,340,000)	(16,300,000)
Interest income	4,000	10,000	24,000	18,000
Interest expense	(875,000)	(391,000)	(2,247,000)	(949,000)
Gain on note repurchase	1,573,000	0
Change in fair value of warrants	(3,000)	(153,000)	334,000	4,158,000
Income (loss) before income tax	417,000	(2,262,000)	(10,229,000)	(13,073,000)
Income tax expense	0	0	4,000	3,000
Net income (loss)	$ 417,000	$ (2,262,000)	$ (10,233,000)	$ (13,076,000)
Net income (loss) per common share:
Basic (in dollars per share)	$ 0.01	$ (0.08)	$ (0.28)	$ (0.59)
Diluted (in dollars per share)	$ 0.01	$ (0.08)	$ (0.28)	$ (0.59)
Weighted-average common shares outstanding
Basic (in shares)	45,432,272	26,803,839	36,147,187	22,287,828
Diluted (in shares)	77,315,056	26,803,839	36,147,187	22,287,828

STOCKHOLDERS' EQUITY (Q1)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023

Equity [Abstract]

STOCKHOLDERS' EQUITY

NOTE 18 – STOCKHOLDERS’ EQUITY

Sponsor Escrow Agreement

Contingent and Earnout Shares

a.	7,000,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $12.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date;

b.	2,250,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $15.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date; and

c.	1,250,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $18.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date.

NOTE 19 – STOCKHOLDERS’ EQUITY

With the consummation of the business combination, Legacy SpringBig. issued and outstanding shares were converted into shares of SpringBig common stock as follows:

	Legacy SpringBig	Conversion Rate	SpringBig
Series B Preferred	4,585,202	0.59289	2,718,522
Series A Preferred	5,088,944	0.59289	3,017,184
Series Seed Preferred	6,911,715	0.59289	4,097,887
Common Stock	14,105,371	0.59289	8,362,933
	30,691,232		18,196,526

Sponsor Escrow Agreement

Contingent and Earnout Shares

The holders of Legacy SpringBig’s common stock and the “engaged option holders” (employees or engaged consultants of Legacy SpringBig who held Legacy SpringBig options at the effective time of the business combination and who remains employed or engaged by Legacy SpringBig at the time of such payment of contingent shares) shall be entitled to receive their pro rata portion of such number of shares, fully paid and free and clear of all liens other than applicable federal and state securities law restrictions, as set forth below upon satisfaction of any of the following conditions:

a.	7,000,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $12.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date;

b.	2,250,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $15.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date; and

c.	1,250,000 contingent shares if the closing price of the Company’s common stock equals or exceeds $18.00 per share on any twenty (20) trading days in a thirty (30)-trading day period at any time after the Closing Date and no later than 60 months following the Closing Date.

The entire disclosure for equity.

CONVERTIBLE NOTE RECEIVABLE (FY) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Apr. 30, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Convertible note receivable			$ 0	$ 259	$ 250
Note receivable, interest rate					5.00%
Convertible debt			0
Impairment loss			116	0
Interest income	$ 4	$ 10	24	$ 18
Convertible Note Receivable, Accrued Interest
Financing Receivable, Allowance for Credit Loss [Line Items]
Impairment loss			272
Interest income			$ 22

CONTRACT ASSETS AND LIABILITIES (Q1) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2024

Dec. 31, 2023