Per the Michigan tax website, you have four years from the original due date of your MI tax return to file for the Homestead Property Tax Credit. Also, if you're not required to file a Michigan tax return, you can submit MI Form MI-1040CR by itself, in order to claim the credit.
https://www.michigan.gov/taxes/property/ind-exempt-defer/homestead-property-tax-credit-information
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
