S.D. Codified Laws § 3-12C-1403
If less than three years of contributory service or noncontributory service is acquired after a retired member's reentry into covered employment, the member upon subsequent retirement shall receive a refund of the member's accumulated contributions.
If three years or more of contributory service or noncontributory service is acquired after a retired member's reentry into covered employment, the member upon subsequent retirement may receive either a refund of the member's accumulated contributions or an additional benefit based upon the member's credited service and final compensation earned during such reentry. Only the member's credited service from the subsequent employment shall be taken into account in calculating a reduction pursuant to § 3-12C-1111, if any, in the member's additional benefit. In addition, the COLA applied to the original benefit pursuant to § 3-12C-703 shall be eliminated for the period of reemployment, unless the member retired as a Class B member other than a justice, judge, or magistrate judge and subsequently reentered covered employment as a Class A member.
The provisions of this section apply to any member who retired without any reduction in benefits pursuant to § 3-12C-1111 and who reenters covered employment after June 30, 2004, but before April 1, 2010.
SDCL 3-12C-1403