CONDENSED PARENT COMPANY ONLY FINANCIAL INFORMATION - CONDENSED STATEMENTS OF INCOME (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
INTEREST INCOME
Investment securities	$ 1,480	$ 674
NON-INTEREST EXPENSE
Professional fees	538	388
Data processing and communication	841	777
Other	367	307
Total non-interest expense	8,720	7,791
Income (loss) before income tax expense (benefit)	159	2,399
Income Tax Expense (Benefit)	(21)	484
NET INCOME	180	1,915
Catalyst Bancorp, Inc.
INTEREST INCOME
Investment securities	173	16
NON-INTEREST EXPENSE
Professional fees	168	22
Data processing and communication	31	11
Franchise tax	63
Other	86	11
Total non-interest expense	348	44
Income (loss) before income tax expense (benefit)	(175)	(28)
Income Tax Expense (Benefit)	(37)	(6)
Income (loss) before equity in undistributed earnings of subsidiary	(138)	(22)
Equity in undistributed earnings of subsidiary	318	1,937
NET INCOME	$ 180	$ 1,915