S.D. Codified Laws § 3-12C-1401

Except as provided in § 3-12C-1401.1, a retired member's retirement is invalid if the member is reemployed by a participating unit unless the member's employment relationship with the initial participating unit has been terminated, as defined in this chapter and as required pursuant to Revenue Ruling 57-115 by the Internal Revenue Service, and the member has been separated from service for three consecutive calendar months after the member's effective date of retirement. The initial participating unit's system representative shall certify to the system that the termination of the employment relationship took place. In addition, any second participating unit shall subject the member to all proceedings and requirements associated with the hiring and employment of any new employee by the second participating unit, and that unit's system representative shall so certify to the system. If a single participating unit is both the member's initial participating unit and the member's second participating unit, the unit shall follow all termination procedures and all hiring procedures relative to the member as outlined by this section, and its chief executive officer, the officer's agent, or the chair of the unit's governing commission or board shall so certify.