S.D. Codified Laws § 5-18A-35

In the procurement of supplies or services, a purchasing agency may require a bond or an approved security to be submitted with any bid or proposal as a guarantee that the bidder will enter into a contract with the purchasing agency. No offeror or bidder may be required to leave the bond or security posted for a longer period than that allowed by § 5-18A-5 if the bid or proposal is not accepted. The bond or approved security of the successful offeror or bidder shall be returned upon the signing of the contract.