Mich. Comp. Laws § 110.17: Improvement before tax levy prohibited.

Sec. 17.

No public work, improvement or expenditure shall be commenced, nor any contract therefor be let or made, except as herein otherwise provided, until a tax or assessment shall have been levied to pay the cost and expense thereof, and no such work or improvement shall be paid for, or contracted to be paid for, except from the proceeds of the tax or assessment thus levied, or from the proceeds of bonds issued in anticipation of the collection of said tax.