1120-S: U.S. Income Tax Return for an S Corporation (2025)

Who files this form

A corporation or other entity must file Form 1120-S if all three conditions apply:

• It elected to be an S corporation by filing Form 2553.
• The IRS accepted the election.
• The election remains in effect.

Use the form to report income, gains, losses, deductions, credits, and other information for a tax year covered by the S corporation election.

Do not file Form 1120-S unless the corporation has filed or is attaching Form 2553. Do not use it for a tax year before the election takes effect.

When it's due

• 2025 calendar-year return: File by March 16, 2026. The instructions explain that March 15 falls on a Sunday.
• Extension request for the 2025 return: Generally, file Form 7004 by the return’s regular due date.
• Tax payment for the 2025 return: Generally, pay any tax due by the regular filing deadline, without extensions.

What you'll need

Have the following information and applicable forms ready:

• Corporation details: Name, address, employer identification number (EIN), incorporation date, S election effective date, business activity code, and number of shareholders during the year.
• Financial records: Income, expenses, assets, liabilities, shareholder distributions and loans, estimated tax payments, and any prior-year overpayment credited to this year.
• S corporation election: Form 2553, if it is being attached rather than already filed.
• Shareholder reporting: Schedules K-1 and applicable supporting statements. International reporting may also require Schedules K-2 and K-3.
• Forms supporting specific items: Examples include Form 1125-A for cost of goods sold, Form 4797 for sales of business property, Form 4562 for depreciation or the section 179 deduction, Form 8825 for rental real estate income, and Schedule D (Form 1120-S) for capital gains and losses.
• Supporting statements: Attach statements where the form requires them, including for other income and other deductions.
• Refund information: For direct deposit, have the corporation’s routing number, account number, and account type ready.

The attachments needed depend on the corporation’s activities and the items it reports.

How to file

Electronic filing

S corporations can generally e-file Form 1120-S and related forms, schedules, statements, and attachments. Some returns are excluded from this option.

A corporation must generally e-file if it files 10 or more returns of any type during the calendar year, including income tax, employment tax, excise tax, and information returns. A hardship waiver may be requested. The instructions also provide a religious exemption when the required technology conflicts with religious beliefs.

For more information, see E-file for Business and Self Employed Taxpayers on IRS.gov.

Filing by mail

Use the address that matches the corporation’s principal business, office, or agency location and its year-end total assets.

Connecticut, Delaware, District of Columbia, Georgia, Illinois, Indiana, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, West Virginia, or Wisconsin:

• If total assets are less than $10 million and Schedule M-3 is not filed, send to: Department of the Treasury, Internal Revenue Service, Kansas City, MO 64999-0013.
• If total assets are $10 million or more, or Schedule M-3 is filed, send to: Department of the Treasury, Internal Revenue Service, Ogden, UT 84201-0013.

Alabama, Alaska, Arizona, Arkansas, California, Colorado, Florida, Hawaii, Idaho, Iowa, Kansas, Louisiana, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, or Wyoming:

• For any asset amount, send to: Department of the Treasury, Internal Revenue Service, Ogden, UT 84201-0013.

A foreign country or U.S. territory:

• For any asset amount, send to: Internal Revenue Service, P.O. Box 409101, Ogden, UT 84409.

For an IRS-designated private delivery service, find the appropriate street address at IRS.gov/PDSStreetAddresses. Private delivery services cannot deliver to P.O. boxes.

Complete and sign the return

Complete every applicable entry on Form 1120-S and Schedule K-1. Attach schedules and other forms after page 5 in the order listed in the instructions. Put supporting statements last, in the order of the forms or schedules they support, and include the corporation’s name and EIN on each attachment.

An authorized corporate officer must sign and date the return. If a receiver, trustee, or assignee files for the corporation, that fiduciary signs instead.

Common mistakes

• Filing without an S corporation election: Do not file Form 1120-S unless Form 2553 has been filed or is attached.
• Putting nonbusiness items on page 1: Lines 1a through 22 must include only trade or business income and expenses.
• Passing through amounts that belong on the corporation’s return: The reminders say certain Form 4255 amounts must be reported directly on Form 1120-S rather than passed through to shareholders.
• Using a private delivery service for a P.O. box: Use the U.S. Postal Service for an IRS P.O. box address.
• Attaching a penalty explanation when filing: The instructions say not to attach one to the return. If the IRS later sends a penalty notice, send an explanation then for the IRS to consider under its reasonable-cause criteria.

Questions people ask

What if the IRS has not confirmed our S corporation election?

If you have not received acceptance or nonacceptance within 2 months after filing Form 2553, call 800-829-4933. Allow 5 months if you checked box Q1 to request a letter ruling.

Does every corporation have to complete Schedules L and M-1?

No. Schedule B, question 11, says these schedules are not required if both total receipts for the tax year and total assets at year-end are less than $250,000. See the instructions for what counts as total receipts.

Can the corporation get its refund by direct deposit?

Yes. Enter the refund amount on line 28b and complete the routing number, account type, and account number on lines 28c through 28e. The corporation can instead apply all or part of its overpayment to 2026 estimated tax on line 28a.

How do we correct a return already filed?

File an amended Form 1120-S and check box H(4) on page 1. Attach a statement identifying each changed line, the corrected amount or treatment, and the reason for the change. If shareholder information on Schedule K-1 or K-3 changes, file the amended schedule with the amended return and give the shareholder a copy.

Official sources

• https://www.irs.gov/pub/irs-prior/f1120s--2025.pdf
• https://www.irs.gov/pub/irs-prior/i1120s--2025.pdf