S.D. Codified Laws § 12-4-19.6

The national change of address notice shall be sent by forwarding service requested to each voter in the active registration file who has failed to vote, has not updated the voter's registration information, has not replied to a confirmation mailing at least once during the last preceding four consecutive years, and has had a national change of address within the jurisdiction with the United States Post Office. This process shall be performed by each county auditor from January first to November fifteenth, inclusive, of each odd-numbered year.