2025 Missouri Form 1040

For tax year 2025, Missouri Form MO-1040 is generally due April 15, 2026. Missouri generally grants an automatic extension until October 15, 2026. If you expect to owe Missouri income tax, file Form MO-60 with your payment by the original due date. An extension gives you more time to file, but not more time to pay any Missouri income tax due. If you owe Missouri income tax, filing or paying late may result in substantial penalties and interest. You are not required to file Missouri Form MO-60 if you do not expect to owe income tax or if you anticipate receiving a refund. See the Extension of Time to File and Late Filing and Payment sections of the instructions booklet for more information.

Use black ink if you print and complete Missouri Form MO-1040 by hand. At the top of the form it says to print in black ink only and not to staple the return. Print your name(s), address, Social Security number(s), and amounts clearly in the spaces provided on the return. Rounding is required on the return. Round cents down for 1 cent through 49 cents, and round up for 50 cents through 99 cents. See the Important Filing Information section of the instructions booklet for related information.

Yes, include Forms W-2 and 1099 when the Missouri instructions require them for your return. Examples include Missouri withholding, pension or Social Security exemptions, and nonresident or part-year resident income reported on Form MO-NRI. Missouri may also require a copy of your federal return in these situations. Review the attachment notices on Form MO-1040, Form MO-NRI, and in the instructions booklet before mailing your return.

Do not include a full copy of your federal income tax return unless the Missouri instructions ask for federal pages, forms, or schedules. Missouri Form MO-1040 uses information from your federal return, so complete your federal tax return first. For example, certain deductions, credits, amended returns, itemized deductions, pension exemptions, and nonresident or part-year resident schedules may require federal Form 1040 pages 1 and 2, federal Schedule A, Forms W-2 or 1099, or other federal forms. Review the attachment notices on Missouri Form MO-1040 and in the instructions booklet before mailing your return.

Yes. To amend a Missouri individual income tax return, file Form MO-1040 and select the Amended Return box. Complete the amended return using the corrected information, including Form MO-A, Individual Income Tax Adjustments, when required. Select the reason for amending your return and attach the schedules or documents needed to support the changes. If the IRS changes your federal return, or you file an amended federal return, Missouri generally requires you to file an amended Missouri return within 90 days of the change. See the Amended Return and Report of Changes in Federal Taxable Income sections of the instructions booklet for more information.

Keep records of income, deductions, credits, and worksheets used to prepare your Missouri tax return at least until the statute of limitations runs out. Try to keep exact copies of your filed Missouri income tax returns even longer. The Missouri Taxpayer Bill of Rights says the Department generally has 3 years from the date the return was filed to issue a notice of deficiency. If you omitted income that should have been reported, and the omitted income is more than 25% of the gross income shown on the return, the period is generally extended to 6 years. There is no period of limitation when no return was filed, or when a false or fraudulent return was filed. See the Statute of Limitations on Deficiencies section of the Missouri Taxpayer Bill of Rights for more information.