South Dakota Codified Laws — Title 10 (Taxation)
SDCL § 10-59-33 — Timely filing by mail of returns, reports or remittances for taxes specified in § 10-59-1--Exceptions
10-59-33 . Timely filing by mail of returns, reports or remittances for taxes specified in § 10-59-1 --Exceptions.
Any return, report, or remittance which is required to be filed under the taxes specified in § 10-59-1 , except as provided for in §§ 10-59-32 and 10-59-32.1 and chapter 10-47B , is timely filed if mailed, postage prepaid, on or before the due date of the reporting period, and is received by the department. 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, report, or remittance is timely filed if mailed, postage prepaid, 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. A United States Postal Service postmark is evidence of the date of mailing for the purpose of timely filing of returns, reports, or remittances.
Source: official text