Any debt due to any bank on which the interest is past due and unpaid for a period of six months unless the debt is well secured or in process of collection, shall be considered a bad debt and be charged to the reserve for loan and lease losses. In no case may an overdraft be held as an asset by any bank for a period of time longer than that set by the rules of the commission. Source: SDC 1939, § 6.0432; SDCL, § 51-11-14; SL 1969, ch 11 , § 4.16; SL 1981, ch 346 , § 35; SL 1988, ch 377 , § 93; SDCL, § 51-18-17; SL 1991, ch 390 , § 6; SL 1997, ch 271 , § 1.