S.D. Codified Laws § 20-4-6
Current with legislation signed by the governor on or before 3/6/2024
Where a debtor, under several obligations to another, does an act by way of performance in whole or in part, which is equally applicable to two or more of such obligations, such performance must be applied as provided by §§ 20-4-7 to 20-4-9, inclusive.
SDCL 20-4-6