S.D. Codified Laws § 3-12C-1103
For any foundation member whose contributory service concluded after June 30, 2021, and before July 1, 2022, the term, final average compensation, means the highest average annual compensation earned by a member during any period of sixteen consecutive calendar quarters during the member's last forty calendar quarters of membership in the system, including time during which the member was not a member but for which the member has received credit under the system.
For any foundation member whose contributory service concluded after June 30, 2022, the term, final average compensation, means the highest average annual compensation earned by a member during any period of twenty consecutive calendar quarters during the member's last forty calendar quarters of membership in the system, including time during which the member was not a member but for which the member has received credit under the system.
For purposes of determining final average compensation if periods of contributory service are separated by breaks, any service earned from covered employment may be aggregated to constitute a period of consecutive calendar quarters.
For any member who has less than the number of calendar quarters of membership considered in the computation of the member's final average compensation, but more than four, the member's final average compensation shall be based on the compensation received in all quarters of membership. For any member who has four calendar quarters of membership or less, the member's final average compensation shall be based on the member's annual compensation.
SDCL 3-12C-1103