SDCL § 10-33A-15: Records to be kept by company--Subject to inspection--Retention period.

Any telecommunications company subject to the telecommunications gross receipts tax shall keep records of all receipts and telecommunications service sales. The records are, at all times during business hours of the day, subject to inspection by the department to determine the amount of tax due. The records shall be preserved for a period of three years unless the secretary, in writing, authorized their destruction or disposal at an earlier date.