S.D. Codified Laws § 10-59-32
The secretary may authorize any person required to file returns or reports and remit taxes or fees under chapters 10-45, 10-45D, 10-46, 10-46A, 10-46B, 10-46E, 10-52, 10-52A, 10-33A, and 10-62, to remit the taxes or fees by electronic transmission. Any person required to file returns and remit taxes who remits taxes by electronic transmission pursuant to this section, as authorized by the secretary, shall file returns by electronic means on or before the twentieth day of the month following each period. If the due date falls on a Saturday, Sunday, legal holiday enumerated in § 1-5-1, or a day the Federal Reserve Bank is closed, the return is due on the next succeeding day that is not a Saturday, Sunday, legal holiday enumerated in § 1-5-1, or a day the Federal Reserve Bank is closed. Remittances transmitted electronically pursuant to this section shall be made on or before the twenty-fifth day of the month following each period. Remittances are considered to have been made on the date that the remittance is credited to the bank account designated by the treasurer of the State of South Dakota. If the due date falls on a Saturday, Sunday, legal holiday enumerated in § 1-5-1, or a day the Federal Reserve Bank is closed, the remittance is due on the next succeeding day that is not a Saturday, Sunday, legal holiday enumerated in § 1-5-1, or a day the Federal Reserve Bank is closed.
SDCL 10-59-32