When should I amend my Michigan return?

Amend your Michigan return only after your original return or claim has been filed and processed. If you are claiming a refund on your amended return, you must file it within four years of the due date of the original return (including approved extensions). For example, to amend a 2018 return that was not extended, the amended return must be received by April 17, 2023. 

If a change on your federal return affects your Adjusted Gross Income (AGI) and/or your exemptions, you must file an amended Michigan return within 16 weeks of the change. Include a copy of your amended federal return with all applicable schedules and supporting documents. Submit payment of any tax and interest due.