Mich. Comp. Laws § 38.1639a

Sec. 39a. (1) Effective October 1, 1996, the monthly retirement allowance payable to a retirant or retirement allowance beneficiary of a deceased retirant or member who meets the requirements of this section is increased 10%. This section only applies to a retirant or retirement allowance beneficiary of a deceased retirant or member who meets all of the following requirements: (a) The retirant's or deceased retirant's effective date of retirement was before October 1, 1986 or the retirement allowance effective date for the retirement allowance beneficiary of the deceased member was before October 1, 1986. (b) The retirant or deceased retirant retired after 25 years of service or because of duty-incurred total disability under section 5 of former Act No. 251 of the Public Acts of 1935 or the retirement allowance beneficiary of a deceased member is receiving duty death benefits under section 8 or former Act No. 251 of the Public Acts of 1935. (c) The retirant or retirement allowance beneficiary was in payment status on the rolls of the retirement system on October 1, 1995. (2) The increased retirement allowance under this section shall be the basis upon which future adjustments to the retirement allowance, including the increases under sections 40 and 40a, if applicable, are calculated.