Michigan Compiled Laws, Chapter 205. Taxation § 205.54z

Sec. 4z. (1) For taxes levied after December 31, 1990 and before July 1, 1999, the tax levied under this act does not apply to a claimed exemption of tangible personal property used in the construction, alteration, repair, or improvement of the real estate or is affixed to and made a structural part of a building of a nonprofit hospital provided the following criteria have been met:

(2) The provisions of this section shall not be applied to affect any final decision of a court.

(3) A claim for refund for an exemption under this section shall be filed not later than July 15, 1999. The approved refunds shall be paid without interest.