Michigan Compiled Laws, Chapter 445. Trade and Commerce § 445.858

Sec. 8.(1) Notwithstanding contrary provisions of a retail installment contract, a buyer may prepay in full the unpaid balance of the retail installment contract at any time before its final due date and, if the buyer does so, shall receive a refund credit for the prepayment, except as provided in section 23.  1 The amount of the refund credit shall not be less than the amount that would be refunded using the actuarial method.

(2) A refund credit of less than $1.00 need not be made.