M4X: Amended Corporation Franchise Tax Return (2025)

Minnesota · Minnesota DOR · Used for tax years 2025

Form M4X is Minnesota’s 2025 Amended Corporation Franchise Tax Return. It reports previously reported amounts, net changes, and corrected amounts for income, deductions, taxes, credits, and payments to determine an amount due or refund.

Who files this form

Use the 2025 Form M4X to claim a refund or report changes to your corporation’s Minnesota tax liability for tax year 2025. File it only after filing your original return.

If you amend your federal return or the IRS adjusts it, you must notify the Minnesota Department of Revenue within 180 days. Attach a copy of the amended federal return or notice of adjustment to Form M4X.

What you'll need

  • Your original Minnesota return and any later amended returns or audit adjustments, to find previously reported amounts.
  • Your corporation’s FEIN, Minnesota Tax ID, tax year beginning and ending dates, and the date you filed the original return.
  • A detailed explanation of each change, including computations and supporting schedules, statements, or forms. Add another sheet if needed.
  • Your amended federal return or IRS adjustment notice, if applicable.
  • Corrected schedules if you change amounts on lines 7, 8, 20 through 25, or 30 through 33.
  • Documentation showing Minnesota backup withholding if you report it on line 34, such as Form 1099, Schedule KPI, Schedule KS, or federal return documentation.
  • Form TPD if you are reporting a Tax Position Disclosure.
  • Your routing number, account number, and account type if you expect a refund. Use an account not associated with any foreign banks.

How to file

  1. Enter your corporation’s identifying information and tax year dates. Check the applicable boxes, including the reason for amending.
  2. Enter previously reported or adjusted amounts in column A. Show changes in column B, using parentheses for decreases. Enter corrected amounts in column C. If an amount has not changed, carry column A into column C.
  3. Explain each change in detail on page 3 and attach the required supporting documents.
  4. Have a person authorized by the corporation sign the return. A paid preparer must also sign and enter their PTIN and phone number.

Mail the return to:

Minnesota Department of Revenue

Mail Station 1255

600 N. Robert St.

St. Paul, MN 55146-1255

Paying an amount due: Go to www.revenue.state.mn.us and select Make a Payment. The instructions provide bank account, credit or debit card, ACH credit, and Fed Wire payment options. Card payments have a vendor fee.

For a check or money order, use the website’s Payment Voucher System to create a voucher. When filing a paper return, send the voucher and payment separately from the return. Electronic payment is required if you meet the requirements stated in the instructions.

Common mistakes

  • Missing signatures or preparer details. An authorized person must sign. A paid preparer must sign and provide their PTIN and direct phone number.
  • Not rounding amounts. Round to the nearest whole dollar. Drop amounts under 50 cents and round amounts of 50 cents or more up to the next dollar.
  • Stapling or taping attachments. Do not staple anything you submit or tape enclosures to the return.
  • Leaving out withholding documentation. Without documentation for line 34, the department will disallow the withholding and assess tax or reduce your refund.
  • Including the wrong amounts on line 36. Do not include payments for penalties, interest, or underpayment of estimated tax.
  • Including refund interest on line 38. Do not include interest paid with refunds you received.
  • Paying by check when electronic payment is required. A 5% penalty applies to payments not made electronically, even if the check is sent on time.
  • Missing the conformity notation. If amending solely because of the 2026 Minnesota tax bill, write “Conformity” in red at the top of Form M4X.

Questions people ask

How will I receive my refund?

You must provide banking information so the full refund can be deposited directly into your account. The account must not be associated with any foreign banks.

Can I apply this refund to estimated tax?

No. The Form M4X refund cannot be applied to your estimated tax account. Estimated payments and refunds credited to later years cannot be amended.

Does Form M4X show my corrected balance if I still owe tax on my original return?

No. If your original Form M4 has unpaid taxes, Form M4X is not intended to show your corrected balance due. Lines 41 and 46 reflect changes to tax or credits reported on the amended return.

Does checking the preparer authorization box let my preparer sign for me?

No. The checkbox allows the department to discuss specified return information with your preparer, but it does not authorize the preparer to sign tax documents for you or represent you at an audit or appeals conference. For those authorities, the instructions require Form REV184b, Business Power of Attorney.

Official sources

All versions of M4X