S.D. Codified Laws § 10-59-33.2
For any return, report, or remittance which is filed under the taxes specified in § 10-59-1, except as provided for in §§ 10-59-32 and 10-59-32.1 and chapters 10-43 and 10-47B, by electronic means, the return or report is timely if received on or before the due date of the reporting 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 or report is due on the next succeeding day which is not a Saturday, Sunday, legal holiday enumerated in § 1-5-1, or a day the Federal Reserve Bank is closed. The remittances transmitted electronically pursuant to this section shall be made on or before the twenty-fifth 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 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 10-59-33.2