What should I do if I received another W-2, or have discovered an error on my return after I filed?

If there is a change to your federal adjusted gross income or the allowable exemptions, Michigan law requires the filing of an amended return, MI-1040X-12 .

You must provide an explanation of the changes on page 2 and include supporting documentation for the changes made on the amended return. (i.e. federal return and schedules, property tax statements, W-2(s), amended Schedule W

An amended return cannot be e-filed. Failure to include an explanation with supporting documentation for the changes made may result in a denial of the return.