Mich. Comp. Laws § 141.954

Sec. 4. (1) The amount due the municipality shall be determined by dividing the estimated equalized value of the state facilities located in the municipality by the sum of the state equalized valuation of the municipality and the estimated equalized value of the facilities, and multiplying the result by the fire protection expenditures of the municipality reported to the director pursuant to section 3(2). (2) A payment shall not be made to a municipality if the amount of the payment is less than $500.00, if the estimated equalized value of the state facility in the municipality is less than 1% of the amount of the state equalized valuation of the municipality, or if the state facility provides its own fire protection.