Mich. Comp. Laws § 125.2668

Sec. 18. (1) The authority shall prepare and approve a budget for the operation of the authority for the ensuing fiscal year. The budget shall be prepared in the manner and contain the information required of municipal departments. Funds of a municipality shall not be included in the budget of the authority except those funds authorized in this act or by the governing body of the municipality. (2) The governing body of a municipality may assess a reasonable pro rata share of the funds for the cost of handling and auditing the funds of the authority, other than those committed for designated purposes, which cost shall be paid annually by the authority under an appropriate item in its budget.