Mich. Comp. Laws § 141.252

Sec. 2. All notes issued under this act are subject to all of the following provisions: (a) For the purpose of computing the amount that may be borrowed, a loan made under this act shall not, when payable as provided in this section, exceed that percentage of the total aggregate revenues derived from state collected taxes returned to a county for county road purposes pursuant to law for the 5 immediately succeeding years: (i) In 10 installments, 40%. (ii) In 9 installments, 36%. (iii) In 8 installments, 32%. (iv) In 7 installments, 28%. (v) In 6 installments, 24%. (vi) In 5 installments, 20%. (vii) In 4 installments, 16%. (viii) In 3 installments, 12%. (ix) In 2 installments, 8%. (x) In 1 installment, 4%. (b) A loan payable in more than 2 installments shall not be authorized for any purpose other than for the construction, improvement, maintenance, or repair of highways. At no time shall the total loans outstanding under this act exceed 40% of the sum of the revenues derived from state collected taxes returned to the county for county road purposes for the immediately preceding 5 calendar years and not specifically allocated for other purposes. (c) The resolution authorizing the borrowing shall contain an irrevocable appropriation providing for the payment of the principal and interest from the money to be derived from state collected taxes returned to the county for county road purposes pursuant to law that have not been previously specifically allocated for other purposes.