Note 15 - Shareholders' Equity and Regulatory Matters - (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]

Business First Bancshares, Inc. (Consolidated)	Actual					For Capital Adequacy Purposes					To Be Well Capitalized Under Prompt Corrective Action Provisions
	Amount		Ratio			Amount		Ratio			Amount		Ratio
	(Dollars in thousands)
December 31, 2023:
Total Capital (to Risk-Weighted Assets)	$	754,990		12.85	%	$	470,215		8.00	%	$	587,769		10.00	%
Tier 1 Capital (to Risk-Weighted Assets)		614,975		10.46	%		352,661		6.00	%		470,215		8.00	%
Common Equity Tier 1 Capital (to Risk-Weighted Assets)		538,045		9.15	%		264,496		4.50	%		382,050		6.50	%
Tier 1 Leveraged Capital (to Average Assets)		614,975		9.52	%		258,407		4.00	%		323,008		5.00	%
December 31, 2022:
Total Capital (to Risk-Weighted Assets)	$	704,840		12.75	%	$	442,391		8.00	%	$	552,988		10.00	%
Tier 1 Capital (to Risk-Weighted Assets)		557,088		10.07	%		331,793		6.00	%		442,391		8.00	%
Common Equity Tier 1 Capital (to Risk-Weighted Assets)		480,158		8.68	%		248,845		4.50	%		359,442		6.50	%
Tier 1 Leveraged Capital (to Average Assets)		557,088		9.49	%		234,859		4.00	%		293,574		5.00	%

											To Be Well
											Capitalized Under
						For Capital					Prompt Corrective
b1BANK	Actual					Adequacy Purposes					Action Provisions
	Amount		Ratio			Amount		Ratio			Amount		Ratio
	(Dollars in thousands)
December 31, 2023:
Total Capital (to Risk-Weighted Assets)	$	730,117		12.43	%	$	469,751		8.00	%	$	587,188		10.00	%
Tier 1 Capital (to Risk-Weighted Assets)		686,379		11.69	%		352,313		6.00	%		469,751		8.00	%
Common Equity Tier 1 Capital (to Risk-Weighted Assets)		686,379		11.69	%		264,235		4.50	%		381,672		6.50	%
Tier 1 Leveraged Capital (to Average Assets)		686,379		10.63	%		258,203		4.00	%		322,754		5.00	%
December 31, 2022:
Total Capital (to Risk-Weighted Assets)	$	657,588		11.91	%	$	441,833		8.00	%	$	552,292		10.00	%
Tier 1 Capital (to Risk-Weighted Assets)		618,805		11.20	%		331,375		6.00	%		441,833		8.00	%
Common Equity Tier 1 Capital (to Risk-Weighted Assets)		618,805		11.20	%		248,531		4.50	%		358,989		6.50	%
Tier 1 Leveraged Capital (to Average Assets)		618,805		10.55	%		234,679		4.00	%		293,348		5.00	%