If you discover a mistake on a previously filed Partnership Tax return, you must correct it by filing Form M3X, Amended Partnership Return/Claim for Refund. Use the most current version of Form M3X, no matter what year return is being amended.
When to File
You may file an amended return within 3½ years of the due date or within 1 year of the date on a tax order (bill), whichever is later. If you filed your original return under an extension, you have 3½ years from the extended due date.
How to File
You must file Form M3X on paper. Enclose any additional lists of changes, amended schedules and a complete copy of your amended federal return (Form 1065). Mail it to:
Minnesota Amended Partnership Tax
Mail Station 1760
St. Paul, MN 55145-1760