S.D. Codified Laws § 3-13C-11
Each participant may name a beneficiary to receive any death benefit due for participation in the plan, other than any income payable to a contingent. The participant may change any beneficiary from time to time. The participant's beneficiary designation and any change of beneficiary shall be subject to the provisions of § 3-13C-13.
It is the responsibility of the participant to give written notice to the system of the name of the beneficiary on a form furnished for this purpose. The system shall maintain a record of each participant's beneficiary designation before the participant's retirement date.
If there is no beneficiary named or surviving when a participant dies, the participant's beneficiary shall be the participant's surviving spouse, or if there is no surviving spouse, the executor or administrator of the participant's estate.
SDCL 3-13C-11