What Form 1120-S is for
Form 1120-S is the income tax return for a corporation or other entity that elected to be an S corporation. You use it to report the company's income, gains, losses, deductions, credits, and other information for any tax year the election covers. The corporation itself pays tax only on a few items listed on lines 23a, 23b, and 23c.
You file it only if you filed Form 2553, the IRS accepted that election, and the election is still in effect. Schedule K adds up all shareholders' shares of income, deductions, and credits. Each shareholder gets a Schedule K-1 with their own share and reports it on their own return, whether or not the money was distributed to them.
Who has to file Form 1120-S?
You file Form 1120-S if your corporation or other entity elected to be an S corporation by filing Form 2553, the IRS accepted that election, and the election remains in effect. Do not file this form unless Form 2553 has been filed or you attach it to the return. Do not file for any tax year before the year the election takes effect. Once the election is made, it stays in effect until it is terminated.
After you file Form 2553 you should receive confirmation that it was accepted. If no notice of acceptance or nonacceptance arrives within 2 months of filing Form 2553, or 5 months if you checked box Q1 to ask for a letter ruling, call 800-829-4933 to follow up. If you have not filed Form 2553 or did not file it on time, the Instructions for Form 2553 cover relief for a late election.
When is Form 1120-S due?
An S corporation generally files Form 1120-S by the 15th day of the 3rd month after the end of its tax year. For calendar year corporations, the due date is March 16, 2026, because March 15 falls on a Sunday. If the due date falls on a Saturday, Sunday, or legal holiday, you can file on the next day that is not one of those. A corporation that has dissolved generally files by the 15th day of the 3rd month after the date it dissolved.
Need more time? File Form 7004 to ask for an automatic extension, generally by the regular due date of the return. An extension of time to file does not move the payment deadline. Interest is charged on taxes paid late even if an extension is granted. You also have to give each shareholder a Schedule K-1 on or before the day Form 1120-S is required to be filed.
Where do you send Form 1120-S?
The address depends on where your principal business, office, or agency is located and on the total assets you report in item F. Corporations in the first group of states below file in Kansas City when total assets are less than $10 million and Schedule M-3 is not filed, and in Ogden otherwise. Corporations in the second group use Ogden at any asset amount. Private delivery services cannot deliver to a P.O. box, so use the U.S. Postal Service for any IRS P.O. box address.
- 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, Wisconsin, with total assets less than $10 million and no Schedule M-3: Department of the Treasury, Internal Revenue Service, Kansas City, MO 64999-0013
- Those same states, with $10 million or more in total assets, or less than $10 million and Schedule M-3 filed: 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, Wyoming, any amount: Department of the Treasury, Internal Revenue Service, Ogden, UT 84201-0013
- A foreign country or U.S. territory, any amount: Internal Revenue Service, P.O. Box 409101, Ogden, UT 84409
- For returns filed on or after January 1, 2024, you must e-file Form 1120-S if you file 10 or more returns of any type during the calendar year, including income tax, employment tax, excise tax, and information returns. You can request a waiver if e-filing would cause a hardship.
How do you fill out Form 1120-S?
Start at the top with the corporation's true name, the address of its principal office, the S election effective date, the business activity code, the EIN, the date incorporated, total assets, and the number of people who were shareholders during any part of the tax year. Lines 1a through 22 hold trade or business income and expenses only. Rental activity income and portfolio income go on Schedules K and K-1 instead, and rental real estate goes on Form 8825.
Line 22 carries ordinary business income or loss to Schedule K, line 1, which sums up all shareholders' shares. You can round cents to whole dollars as long as you do it for every amount on the return. Drop amounts under 50 cents and raise 50 to 99 cents to the next dollar, so $8.40 becomes $8 and $8.50 becomes $9. Fill in every applicable entry space. Do not write 'See Attached' or 'Available Upon Request' in place of an entry.
The return has to be signed and dated by the president, vice president, treasurer, assistant treasurer, chief accounting officer, or another corporate officer authorized to sign. If a receiver, trustee, or assignee files for the corporation, that fiduciary signs instead. Anyone paid to prepare the return signs it, includes a Preparer Tax Identification Number, and fills in the Paid Preparer Use Only area. An employee of the corporation who prepares the return leaves that area blank.
What changed on the 2025 Form 1120-S?
The minimum penalty for filing more than 60 days late went up. For returns required to be filed in 2026, it is the smaller of the tax due or $525. Direct deposit fields for refunds were added at lines 28c, 28d, and 28e. If line 27 shows an overpayment, enter the part you want refunded on line 28b and complete the bank information. You can still credit all or part of the overpayment to next year's estimated tax on line 28a.
New section 174A lets you deduct domestic research and experimental expenditures paid or incurred in tax years beginning after 2024, or elect to charge them to a capital account and amortize them over a period of not less than 60 months. Section 139L allows a qualified lender to exclude 25% of interest income on loans secured by rural or agricultural real property for tax years ending after July 4, 2025. Line 17d picked up new codes BA and ZZ for reporting these items.
Qualified sound recording production costs became an elective expense deduction under section 181 for productions that commence in a tax year ending after July 4, 2025, and before January 1, 2026. Productions acquired after January 19, 2025, are eligible for the 100% special depreciation allowance. For sales or exchanges of qualified farmland property to qualified farmers in tax years beginning after July 4, 2025, attach a separate Schedule A (Form 1062) for each sale.
What if you need to amend the return or end the S election?
To correct a Form 1120-S you already filed, file an amended Form 1120-S and check box H(4) on page 1. Attach a statement that identifies the line number of each amended item, the corrected amount or treatment, and the reason for each change. If the information you gave a shareholder on Schedule K-1 or K-3 was wrong, file an amended one with the amended return, check the Amended K-1 or Amended K-3 box at the top, and give that shareholder a copy.
Item H holds the other status boxes: final return, name change, address change, amended return, and S election termination. Check Final return if the corporation will no longer exist, and also check the Final K-1 box on each Schedule K-1. If the S election terminated during the tax year and the corporation reverted to a C corporation, file Form 1120-S for the S corporation's short year by the due date, including extensions, of the C corporation's short year return.
Form 1120-S line by line
| Line | What goes there |
|---|---|
| 1a | Gross receipts or sales from all business operations, except amounts that must be reported on lines 4 and 5. |
| 1b | Cash and credit refunds you made to customers for returned merchandise, plus rebates and other allowances. |
| 2 | Cost of goods sold. Complete Form 1125-A and enter the amount from its line 8. |
| 4 | Ordinary gain or loss from Form 4797, Part II, line 17, on trade or business assets sold, exchanged, or involuntarily converted. |
| 5 | Other trade or business income or loss not included on lines 1a through 4. List the type and amount on an attached statement. |
| 7 | Total compensation of all officers. Attach Form 1125-E if the corporation's total receipts are $500,000 or more. |
| 8 | Total salaries and wages paid to employees other than officers, less employment credits. |
| 20 | Other allowable trade or business deductions not entered elsewhere. Attach a statement listing each one by type and amount. |
| 22 | Ordinary business income or loss: line 6 minus line 21. Enter the same figure on Schedule K, line 1. |
| 26 | Amount owed, if line 24z is smaller than the total of lines 23c and 25. Payment must be made electronically. |
| 27 | Overpayment, if line 24z is larger than the total of lines 23c and 25. |
| 28c | Routing number for a direct deposit refund. It must be nine digits, with the first two between 01 and 12 or 21 through 32. |
| Schedule B | Other information: accounting method, business activity, ownership of other entities, Form 1099 payments, and the digital asset question. |
| Schedule K | All shareholders' pro rata shares of income, deductions, and credits. Every corporation completes it, and each shareholder's own share goes on a Schedule K-1. |
Penalties and withholding
$255
Per month, up to 12 months, times the number of shareholders, when a late return shows no tax due.
5%
Of the unpaid tax for each month the return is late, added to the penalty above when tax is due.
25%
Cap on the late filing penalty and on the late payment penalty, as a share of the unpaid tax.
$525
Minimum penalty if a return required to be filed in 2026 is more than 60 days late, or the tax due if smaller.
1/2 of 1%
Of the unpaid tax for each month or part of a month the tax is not paid.
$340
For each Schedule K-1 or K-3 not furnished to a shareholder on time or missing required information.
$680
Each $340 penalty if the failure to report correct information is intentional, or 10% of the items if greater.
Source: IRS, Form 1120-S (Rev. 2025) and Instructions for Form 1120-S, U.S. Income Tax Return for an S Corporation. This page explains the form in plain English. It is not tax advice.