S.D. Codified Laws § 58-17A-3.1
A policy or certificate of insurance providing medicare supplement benefits which is sold to a consumer to replace an existing, in-force medicare supplement policy may not contain any provision limiting payment of benefits due to preexisting conditions of the insured except, if there is any time period remaining relating to the exclusion of coverage for preexisting conditions as specified in the underlying policy, that remaining waiting period for coverage of preexisting conditions shall apply to the new policy unless the policy otherwise provides a lesser waiting period. The waiver applies to all time periods applicable to preexisting conditions, waiting periods, elimination periods, and probationary periods in the new medicare supplement.
SDCL 58-17A-3.1