Mich. Comp. Laws § 554.546

Sec. 26. Except as provided in section 27, the custodian shall transfer in an appropriate manner the custodial property to the minor or to the minor's estate upon the earlier of the following: (a) The minor becoming 18 years of age with respect to custodial property transferred under section 8, 9, 10, or 11. (b) The minor's death.