If you find a mistake on your state Individual Income Tax return after it is filed, you must file
Form M1X, Amended Minnesota Income Tax, to correct the error. However, if you’re married and filed a joint return, you can’t change your filing status to “married filing separately” after the due date (April 15 for most people).
Deadline for Amending
To claim a refund, you must file Form M1X within 3½ years of the original due date for your return. (
Prior year forms)
If you amend your federal return, or if the Internal Revenue Service changes or audits it, you must notify the Minnesota Department of Revenue within 180 days, as outlined below.
If the changes affect your Minnesota tax return: You must file Form M1X and include a complete copy of your amended federal return or correction notice. Send your amended return to:
Minnesota Amended Individual Income Tax
Mail Station 1060
St. Paul, MN 55145-1060
If the changes don’t affect your Minnesota return: You must send us a letter of explanation and a complete copy of your federal amended return or correction notice. Send your “no change” letter to:
Minnesota Department of Revenue
Mail Station 7703
St. Paul, MN 55146-7703
If you don’t amend your Minnesota return or notify the department as required, we’ll charge a 10 percent penalty on any additional tax you owe.
When filing your amended return, you must pay any additional Minnesota tax and interest that you owe or we’ll charge you a late-payment penalty.