Minn. Stat. § 426.12
It shall be the duty of every board or department, on the first day of each calendar month and at such other times as the city comptroller, in writing, may demand, including such further information as the city comptroller may demand, to furnish the city comptroller with an accurate and complete statement, properly attested by the proper officer, of all its acts, including all the names, addresses, kind of labor, and compensation to be paid to each of its employees and duration thereof, and when any board or department expends, or is about to expend, money for the purchase of any lands, goods, materials, labor, supplies, or anything of value, and enters into a written contract therefor, the board or department shall immediately furnish the city comptroller with a certified duplicate copy thereof; and no contract shall be valid unless countersigned by the city comptroller.
Minn. Stat. § 426.12
(1445) 1909 c 374 s 2