S.D. Codified Laws § 54-4-44
After procuring such license from the Division of Banking, the licensee may engage in the business of making loans and may contract for and receive interest charges and other fees at rates, amounts, and terms as agreed to by the parties which may be included in the principal balance of the loan and specified in the contract. However, no licensee may contract for or receive finance charges pursuant to a loan in excess of an annual rate of thirty-six percent, including all charges for any ancillary product or service and any other charge or fee incident to the extension of credit. A violation of this section is a Class 1 misdemeanor. Any loan made in violation of this section is void and uncollectible as to any principal, fee, interest, or charge.
SDCL 54-4-44