How to File a Missouri Tax Amendment

If you need to change or amend an accepted Missouri State Income Tax Return for the current or previous Tax Year, you need to complete Form MO-1040 for the appropriate Tax Year. Form MO-1040 is a Form used for the Tax Amendment. You can prepare a current tax year Missouri Tax Amendment on, 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.

File a current tax year Missouri Tax Amendment
You can prepare a Missouri Tax Amendment for the current tax year here on; the amendment can not be e-filed. After you have prepared the amendment, download the PDF from your My Account, check the box and mail in the form to the address listed below. For other tax years complete the form below before you print, sign and mail in the form.
Option 1: Sign into your 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 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.
Check this box on the MO Tax Return Form MO-1040. This Form can be used to file a: Tax Return, Tax Amendment, Change of Address.

Missouri Amendment

Tax Year current tax year only: Prepare online on until the October deadline. When done Print, Sign and Mail in - not eFile - Your Tax Amendment, Address Change, etc.
After the October deadline, Prepare, Print, Sign and Mail-In - see address above - your current tax year - Form MO-1040.
How to correct a rejected Tax Return
If your MO Tax Return was rejected by the MO Tax Agency - not - instructions on how to correct a rejected Missouri Tax Return.
Check Your MO Tax Amendment Status
1. Call the MO Department of Revenue at 573-751-3505.
2. Contact the MO Department of Revenue
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
Missouri Income Tax Penalties
Find out how Missouri Late Filing and Late Payment Penalties are calculated.
For IRS Tax and Late Filing Penalties we have an easy to use tool: The PENALTYucator.
File an IRS Tax Amendment by Tax Year
Instructions on how to prepare an IRS Tax Amendment on, however the IRS does not accept Tax Amendments electronically.

Will I get a bigger tax refund in 2024?

Many taxpayers can expect a bigger tax refund on their 2023 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 2023 taxes, which is the tax return you'll file in 2024.

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 2023 Tax Refund Calculator to get a high-level understanding of your taxes.