Loans and Allowance for Credit Losses - Categories of Loans (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Categories of loans
Total loans	$ 148,690,458
Undisbursed loans in process	2,309,368
Net deferred loan fees	339,455
Allowance for credit losses	963,268
Net loans	145,078,367
Categories of loans
Total loans		$ 133,805,557
Undisbursed loans in process		2,578,282
Net deferred loan fees		325,621
Allowance for credit losses		934,331	$ 983,654
Net loans		129,967,323
Real estate loan
Categories of loans
Total loans	78,244,527
Real estate loan \| Residential
Categories of loans
Total loans	73,285,469
Allowance for credit losses	691,852
Categories of loans
Total loans		74,561,278
Allowance for credit losses		738,230	623,649
Real estate loan \| Multi-family
Categories of loans
Total loans	1,259,640
Allowance for credit losses	2,525
Categories of loans
Total loans		1,309,586
Allowance for credit losses		12,840	11,008
Real estate loan \| Agricultural
Categories of loans
Total loans	53,523,748
Allowance for credit losses	107,284
Categories of loans
Total loans		36,378,192
Allowance for credit losses		73,608	199,011
Real estate loan \| Commercial
Categories of loans
Total loans	2,453,082
Allowance for credit losses	4,917
Categories of loans
Total loans		2,311,882
Allowance for credit losses		4,678	10,801
Real estate loan \| Construction
Categories of loans
Total loans	6,024,429
Allowance for credit losses	92,660
Categories of loans
Total loans		5,082,863
Allowance for credit losses		49,835	35,292
Real estate loan \| Home equity line of credit (HELOC)
Categories of loans
Total loans	4,959,058
Allowance for credit losses	14,910
Categories of loans
Total loans		4,708,023
Allowance for credit losses		14,289	69,234
Commercial and industrial
Categories of loans
Total loans	1,666,188
Allowance for credit losses	3,314
Categories of loans
Total loans		1,801,569
Allowance for credit losses		3,645	12,086
Consumer
Categories of loans
Total loans	5,518,844
Allowance for credit losses	$ 45,806
Categories of loans
Total loans		7,652,164
Allowance for credit losses		$ 37,206	$ 22,573

Mercer Bancorp, Inc. 10-K