Mich. Comp. Laws § 31.12: Emergency successor; oath of office, filing.

Sec. 12.

Promptly after his designation in writing to the secretary of state by the designating authority, each emergency interim successor shall take the oath of office for the office to which he has been designated, and no other oath shall be required. The oath shall be administered by any person authorized to administer oaths in this state, and filed with the secretary of state.