S.D. Codified Laws § 10-33-4

The president, secretary, general manager, or superintendent of each telephone company not subject to the tax imposed by § 10-33-21 shall furnish to the Department of Revenue on or before April fifteenth, each year, a report under oath, on the forms furnished and according to the instructions issued by the department, with reference to the property owned, leased, or controlled on December thirty-first of the preceding calendar year.