Michigan Compiled Laws, Chapter 445. Trade and Commerce § 445.859

Sec. 9. The holder of an installment contract or retail charge agreement, or retail charge agreement including a contract subject to section 23,  1 if it so provides, may collect a delinquency and collection charge on each installment in default for a period of more than 10 days.A delinquency and collection charge is not a liquidated damage.