MO-1120S: S Corporation Income Tax Return (2025)
Missouri · Missouri DOR · Used for tax years 2025
Form MO-1120S is Missouri’s S-Corporation Income Tax Return for 2025. It reports Missouri additions and subtractions and allocates the resulting adjustment among shareholders.
Who files this form
Form MO-1120S is Missouri’s S Corporation Income Tax Return for tax year 2025.
The form asks whether the S corporation has Missouri modifications, nonresident shareholders, or income from sources outside Missouri. It does not state the full rules for which S corporations must file.
What you'll need
Have the following information and documents available for the parts of the return that apply:
- Corporation name, address, charter number, Missouri tax ID number, federal employer ID number, and tax-year beginning and ending dates.
- Federal Form 1120S information for state and local income taxes deducted on the federal return.
- Federal Schedule K-1s for shareholder ownership percentages, plus each shareholder’s name, Social Security number, and nonresident status.
- Amounts for the Missouri additions and subtractions listed on the form, such as interest, related expenses, state income tax refunds, and depreciation adjustments.
- Form MO-NRS if the corporation has nonresident shareholders.
- Form MO-MSS if the corporation has income from sources outside Missouri.
- A copy of approved Federal Extension Form 7004 if claiming an approved federal extension.
How to file
- Enter the corporation’s identifying information and tax-year dates. Select any applicable status boxes.
- Answer the three questions on page 1. If the corporation has Missouri modifications, complete Lines 1–15 and the shareholder information on page 3. If it has nonresident shareholders, also complete Form MO-NRS. If it has income from sources outside Missouri, complete and attach Form MO-MSS.
- If you have an approved federal extension, select the extension box and attach a copy of approved Form 7004.
- Complete the officer’s signature block and the applicable preparer information.
Mail the return to:
Missouri Department of Revenue
P.O. Box 336
Jefferson City, MO 65105-0336
Common mistakes
- Not marking an address change. The form warns that mail may go to the last address on file if you do not select the address change box.
- Leaving shareholders off page 3. All shareholders must be listed. Use an attachment if necessary.
- Not rounding shareholder percentages. Column 4 requires percentages from federal Schedule K-1s rounded to whole numbers.
- Not identifying the adjustment type. At the top of Column 5, indicate whether the adjustments are additions or subtractions.
- Not reporting an unsigned paid-preparer return. If a paid preparer failed to sign or provide their IRS preparer tax identification number, answer the form’s question and enter their name, address, and phone number in the applicable signature-block sections.
Questions people ask
What if the corporation has nonresident shareholders?
Complete Lines 1–15 on pages 1 and 2, the shareholder information on page 3, and Form MO-NRS.
What if the corporation has income from outside Missouri?
Complete and attach Form MO-MSS.
How are Missouri adjustments allocated to shareholders?
Enter the adjustment from Line 13 or 14 as the total of Column 5. Multiply each shareholder’s percentage in Column 4 by that total. Each shareholder must report their amount as an addition or subtraction on Form MO-1040.
Where can I ask questions about the return?
Call (573) 751-4541 or email corporate@dor.mo.gov. The form also lists dor.mo.gov/taxation/business/tax-types/corporation-income/ for additional information.