Mich. Comp. Laws § 38.2210
The reserve for member contributions is created. The retirement system shall deposit contributions from the compensation of members, and other member payments as provided in this act, except member contributions for health benefits as provided in section 305, in the reserve for member contributions. The retirement system shall provide for the maintenance of an individual account for each member showing the amount of the member's accumulated contributions. Except as provided in section 212, the retirement system shall pay accumulated contributions as provided in this act from the reserve for member contributions. If a person ceases to be a member, any unclaimed balance of accumulated contributions remain in the reserve for member contributions. If a member's accumulated contributions are forfeited by the member, as provided in this act, the retirement system shall transfer the forfeited accumulated contributions from the reserve for member contributions to the reserve for investment income. Upon the retirement of a member, the retirement system shall transfer the accumulated contributions of the member from the reserve for member contributions to the reserve for retirement benefits.
MCL 38.2210