Mich. Comp. Laws § 205.223

Sec. 23. Notwithstanding any other provisions of this act, the following apply: (a) Sections 1 through 22 apply only to the estate of a resident or nonresident decedent dying before October 1, 1993 or to a generation-skipping transfer that occurs after December 31, 1992 but before October 1, 1993. (b) Sections 31 to 56 apply only to the estate of a resident or nonresident decedent dying after September 30, 1993 or to a generation-skipping transfer that occurs after September 30, 1993.