S.D. Codified Laws § 58-17H-41

If the covered person or, if applicable, the covered person's authorized representative has failed to provide sufficient information for the health carrier to make a determination, the health carrier shall notify the covered person or, if applicable, the covered person's authorized representative, either orally or, if requested by the covered person or the covered person's authorized representative, in writing of this failure and state what specific information is needed as soon as possible, but in no event later than twenty-four hours after receipt of the request.