How to File a Missouri Tax Amendment
If you need to change or amend an accepted Missouri State Income Tax Return for the 2024 or previous Tax Year, you need to complete Form MO-1040for the appropriate Tax Year. Form MO-1040 is a Form used for the Tax Amendment. You can prepare a 2024 tax year Missouri Tax Amendment on eFile.com, however you cannot submit it electronically. In comparison, the IRS requires a different Form - Form 1040X - to amend an IRS return (do not use Form 1040 for an IRS Amendment).
The IRS might send you a notification to change an error on your Return, or you might have discovered an error. If you or the IRS amended or changed one of your IRS Tax Return(s), the IRS will report this to the Missouri Tax Agency, thus you should file a Missouri Amendment within one year.
Prepare only a MO State Return
File a 2024 tax year Missouri Tax Amendment
You cannot eFile a MO Tax Amendment anywhere, except mail it in. However, you can prepare it here on eFile.com.
Option 1: Sign into
your eFile.com account, modify your Return and download/print the MO
Form MO-1040
under
My Account.
Check the "Amended Return" box, sign the form, and mail it to the address below.
Option 2: If you don't have an eFile.com account follow the step by step
instruction on how to prepare a tax return/amendment.
Option 3: If you want to do the math on your own paper return then complete, sign
Form MO-1040 - Print, Mail the Form to MO Tax Department to:
Department of Revenue
P.O. Box 3370
Jefferson City, MO 65105-3370
MO Tax Amendment Form MO-1040
This Form can be used to file a: Tax Return, Tax Amendment, Change of Address. Check the "Amended Return" box on the Form.
Step 1: Download, Complete Form MO-1040 for the appropriate Tax Year below.
Step 2: Sign, Mail Your Amended Return to the address listed above.
For all Tax Years prior to 2024 tax year Prepare, Print, Sign and Mail-In - see address above - your Tax Amendment as soon as possible. Select the Form MO-1040 for the Tax Year you are amending. You will also file
an IRS Tax Amendment Form 1040X.
Missouri Refund Deadlines
A. Three years from the due date of the original tax year return, including valid filing extensions.
B. One year from the final determination of the amended federal return or federal change, whichever is later, provided that the allowable refund is not more than the decrease in Missouri tax attributable to the federal change or correction.
C. Two years from the payment of an assessment, provided the amended return raises issues relating only to the prior assessment and the refund does not exceed the amount of tax paid on the prior assessment.
D. Two years from the filing of an amended Missouri return resulting in the payment of additional tax, provided that the current amended return raises issues relating solely to the prior amended return and that the refund does not exceed the amount of the tax payment made as a result of the prior amended return.
Additional Missouri Tax Income Taxes Deadlines
Will I get a bigger tax refund in 2026?
Many taxpayers can expect a bigger tax refund on their 2025 taxes. To help you keep up with soaring inflation, the IRS is making bigger changes than usual that could save you big money on your 2025 taxes, which is the tax return you'll file in 2026.
Take control of your personal life relationships, finances, and taxes: follow the tips on this page and keep up with tax planning for next year. You can use this free 2025 Tax Refund Calculator to get a high-level understanding of your taxes.
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