Individual income tax returns were supposed to be filed by July 15 in Michigan -- an-already extended deadline amid the coronavirus (COVID-19) pandemic. State income tax returns can be claimed within four years. For Michigan tax filers who missed the July 15 deadline, the state treasury listed the following actions to consider:Filing a return to claim an outstanding refund. Taxpayers risk losing their state income tax refund if they dont file a return within four years from the due date of the original return. For more information or an application, visit www.michigan.gov/oicOfficials say the last three options listed above should be filed separately from the state income tax return.