S.D. Codified Laws § 3-12C-808
When a person who is receiving a disability benefit reaches age sixty-five, or at such later date if there are no eligible children, or if over age sixty at the time of commencement of disability, after a period of five years, the member's disability benefit shall be terminated and thereafter the member shall receive the benefit payable for service retirement at that age, calculated on the projected compensation and projected service. If a person who received a disability benefit returns to employment prior to normal retirement age, the member's credited service shall include the time of disability. The provisions of this section apply to any member whose application for disability benefits is received by the system prior to July 1, 2015.
SDCL 3-12C-808