Mich. Comp. Laws § 38.572

Sec. 2. The amount of interest used according to the provisions of this act shall be included as interest and other earnings on the money of the retirement system in the computation of any city, village, township, or county liability for regular interest. These supplemental benefits shall not be considered an increase in the rate of retirement allowances to be paid. They shall be on a year-to-year basis and shall not create a liability for their continuance.