Michigan Compiled Laws, Chapter 38. Civil Service and Retirement § 38.2502

Sec. 502. A member who leaves office for a reason other than the member's retirement or death, who does not withdraw accumulated contributions, and who satisfies the service or term of office requirements of section 501(1)  1 is a vested former member. Subject to section 501, a vested former member is entitled to a deferred vested service retirement allowance computed pursuant to section 503  2 or, if applicable, section 13a of former Act No. 198 of the Public Acts of 1951  3 or section 15 of former Act No. 165 of the Public Acts of 1954,  4 as in effect at the time of termination of the vested former member's tenure in office. The vested former member shall forfeit his or her entitlement to a deferred vested service retirement allowance if the vested former member withdraws from the retirement system his or her accumulated contributions unless the service is reinstated as provided in section 402.  5