If you're unable to complete and file your return by the due date, you may avoid penalty and interest by paying your tax by April 15. Estimate your total tax and pay the amount you owe electronically, by check or by credit or debit card. If you pay by check, use Minnesota Department of Revenue's Payment Voucher System . Do not send in an incomplete Form M1.
To avoid a late filing penalty, you must file your return by October 15, 2021.