S.D. Codified Laws § 36-21A-80
A responsible broker shall remit immediately to the responsible broker's principal all money received by the responsible broker belonging to the principal unless, by the terms of a written employment contract, the responsible broker is authorized to retain possession of the money until the final settlement and consummation of the transaction. In that event the responsible broker shall deposit the money in a federally insured financial institution in a special trust account on the first legal banking day after the acceptance of the contract. The account shall be reconciled to the bank statements, trust ledger, and check register at least monthly. The money may not be used by the responsible broker except in connection with the transaction as authorized by the principal.
SDCL 36-21A-80