M8X: Amended S Corporation Return (2025)
Minnesota · Minnesota DOR · Used for tax years 2025
Minnesota Form M8X is used to amend a previously filed 2025 Form M8, S Corporation Return. It reports previously reported amounts, net changes, and corrected amounts for taxes, fees, credits, and payments to determine the amount due or refund.
Who files this form
S corporations must use Form M8X to correct an original Minnesota Form M8, S Corporation Return. File it only after filing the original return. Use this version to amend tax year 2025. For another tax year, use that year's Form M8X.
You must also amend your Minnesota return if the IRS changes or audits your federal return, or you amend your federal return.
S corporations affected by changes in the 2026 Minnesota tax bill must amend using Form M8X and update Schedules KSNC and KS as directed. If amending solely for those changes, write “Conformity” in red at the top of Form M8X and the amended Schedules KS issued to shareholders.
Form M8X can also be used to claim a refund and report changes to Minnesota tax liability.
What you'll need
- Your original Form M8 and any earlier amended returns, audit reports, or adjustment notices needed to determine previously reported amounts.
- The Form M8 instructions for tax year 2025.
- A separate statement explaining each change in detail, including computations.
- Corrected schedules and related forms for amounts you change. Follow the special conformity directions for Schedules KS, KSNC, and PTE when applicable.
- A complete copy of your amended federal Form 1120S, if any. For an IRS adjustment, attach a complete copy of your amended federal return or the IRS correction notice.
- Applicable supporting documents requested on the form, such as S corporation tax computations, Schedules PTE, KS, ETP, and EPC, and credit certificate numbers.
- Your bank routing and account numbers if requesting direct deposit.
How to file
- Enter the corporation's identifying information and the beginning and ending dates of the tax year being amended. Mark the applicable boxes, including the reason for amending.
- For lines 1–16, enter previously reported or adjusted amounts in column A. Enter each increase or decrease in column B, using parentheses for decreases. Leave column B blank where nothing changes. Enter corrected amounts in column C, copying column A where there is no change.
- Complete the remaining tax, payment, and refund lines. Attach your explanations, computations, and required supporting documents.
- Have the principal officer sign. If someone else prepared the return, that preparer must also sign and include their PTIN and phone number.
- Mail the return to:
Minnesota S Corporation Tax
Mail Station 1770
600 N. Robert St.
St. Paul, MN 55146-1770
Payment: Pay electronically through e-Services at www.revenue.state.mn.us. For payment by check, visit that website, select Make a Payment, then Check, and create a voucher using the Payment Voucher System.
Common mistakes
- Missing signatures: The principal officer must sign. A paid preparer must also sign and provide their PTIN and daytime phone number.
- Using staples or tape: Do not staple anything you submit or tape enclosures to the return.
- Leaving changes unexplained: Enter each changed amount and include a detailed explanation and corrected schedules. Missing changed amounts will delay processing.
- Not rounding: Round to the nearest dollar. Drop amounts below 50 cents and round amounts of 50 cents or more up to the next dollar.
- Changing restricted items: Estimated payments and refunds credited to later years cannot be changed after the original return is filed. Form AWC can only be filed with the original return.
- Including the wrong amounts: Do not include penalties, interest, or estimated-tax underpayment amounts on line 17. Do not include refund interest on line 19.
- Using a foreign bank account: Electronic payments cannot use a foreign bank account. Refund direct deposits must use an account not associated with any foreign banks.
Questions people ask
Can I have my refund directly deposited?
Yes. Complete line 27 with your checking or savings account information. Otherwise, you will receive a check. If the bank information is incorrect or your financial institution does not accept it, the refund will be sent as a paper check.
Can I apply my amended-return refund to estimated taxes?
No. The refund cannot be applied to your estimated tax account.
Does Form M8X show my full corrected balance if I still owe tax on the original return?
No. If you have unpaid taxes on the original Form M8, Form M8X is not intended to show your corrected balance due.
Do shareholders need information about the changes?
Yes. The S corporation should provide enough information for shareholders to file accurate amended income tax returns. This may include amended federal Schedules K-1 and Schedules KS. Shareholders must amend their returns to reflect the changes and calculate the change in tax due.
Can I authorize the department to discuss the return with my preparer?
Yes. Check the authorization box on the return. This does not authorize the preparer to sign tax documents for you or represent you at an audit or appeals conference. Those authorities require Form REV184b, Business Power of Attorney.