Internal Revenue Service
Fill out Form 1120-S online
U.S. Income Tax Return for an S Corporation
Form 1120-S reports the income, gains, losses, deductions, credits and other information of a domestic corporation or other entity for a tax year covered by an election to be an S corporation. It shows the totals that pass through to the shareholders on Schedule K, and each shareholder's share goes on a separate Schedule K-1. The corporation itself is liable for the taxes on page 1, lines 23a to 23c, such as the excess net passive income tax and the built-in gains tax from Schedule D (Form 1120-S).
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- Edition
- Tax year 2025
- Pages
- 5
- Fillable fields
- 390
- Checked against the IRS
- November 8, 2026
GuruPDF is not affiliated with the Internal Revenue Service. This page explains the form in plain words; it is not legal or tax advice. Always check the official instructions before you file. This is the tax year 2025 version; the IRS keeps forms for earlier years.
Who uses Form 1120-S
- Domestic corporations that elected S corporation status on Form 2553, when the IRS accepted the election and it is still in effect
- Other entities covered by an election to be an S corporation
- Corporations electing S status beginning with this tax year (item G)
- S corporations filing a final return or an amended return, or a return for the S short year when the election ended during the year
- Corporate officers and paid preparers who complete and sign the return
Before you start
- The corporation's EIN, its legal name as set out in its charter, and the address of its principal office
- The S election effective date, the date of incorporation, and the business activity code from the list at the end of the instructions
- The corporation's books for the tax year: gross receipts, cost of goods sold and each type of expense
- Balance sheets at the beginning and end of the year, unless the answer to Schedule B, question 11, is Yes
- The number of shareholders during the year and the information needed for each shareholder's Schedule K-1
- Records of estimated tax payments and any deposit made with Form 7004, plus the bank routing and account numbers if you want a refund by direct deposit
How to fill out Form 1120-S
Fill in the tax year, name, address and items A to J
Fill in the tax year space at the top only for a fiscal or short tax year. Enter the corporation's legal name as shown in its charter and the address of its principal office or place of business, not the address of a registered agent. Item A is the S election effective date, B is the business activity code, D is the EIN, E is the date of incorporation, and F is total assets at the end of the year, taken from Schedule L, line 15, column (d), when Schedule L is required. If the EIN has not arrived by the due date, a paper return can show "Applied for" and the date of the application; an e-filed return needs the EIN. Check box C if Schedule M-3 is attached. Item G asks whether the corporation is electing S status beginning this year, H has boxes for a final return, name change, address change, amended return or S election termination, I is the number of shareholders during any part of the year, and J is for aggregated or grouped activities.
Report income and deductions (lines 1a to 22)
Include only trade or business income and expenses on lines 1a through 22; rental activity income and portfolio income are reported on Schedules K and K-1 instead. Enter gross receipts on line 1a, returns and allowances on line 1b and the balance on line 1c, then cost of goods sold on line 2 (attach Form 1125-A), the gain or loss from Form 4797 on line 4 and other income on line 5 with a statement. Deductions run from compensation of officers on line 7 (attach Form 1125-E when the instructions require it) and salaries and wages on line 8 through other deductions on line 20, with depreciation from Form 4562 on line 14 and the energy efficient commercial buildings deduction (Form 7205) on line 19. Line 21 is total deductions, and line 22, ordinary business income or loss, is also entered on Schedule K, line 1.
Figure tax and payments (lines 23a to 28e)
Line 23a is the excess net passive income or LIFO recapture tax, line 23b is the tax from Schedule D (Form 1120-S), and line 23c adds them together with any other amounts the instructions list. Lines 24a to 24d are estimated tax payments and last year's overpayment credited to this year, tax deposited with Form 7004, the credit for federal tax paid on fuels (Form 4136) and the elective payment election amount from Form 3800; line 24z is their total. Line 25 is the estimated tax penalty (check the box if Form 2220 is attached), and lines 26 and 27 show the amount owed or the overpayment. On line 28, split an overpayment between next year's estimated tax (28a, a choice that cannot be changed later) and a refund (28b), and enter the routing number, account type and account number on lines 28c to 28e for direct deposit.
Sign the return
An authorized officer signs and dates the return in the Sign Here area and enters their title. Check Yes or No to say whether the IRS may discuss the return with the preparer shown; Yes covers only that individual preparer, not the firm. A paid preparer completes the Paid Preparer Use Only area with their name, signature, date, PTIN and firm details. Leave that area blank if an employee of the corporation prepared the return, or if the preparer did not charge for it.
Answer Schedule B, questions 1 to 17
Schedule B, on pages 2 and 3, asks for the accounting method and the business activity and product or service, followed by Yes or No questions. Question 3 asks whether any shareholder was a disregarded entity, trust, estate or nominee (if Yes, attach Schedule B-1), and question 4 asks about ownership of other corporations, partnerships and trusts, with a table to complete for each one. Later questions cover restricted stock and options, Form 8918, original issue discount debt, net unrealized built-in gain, business interest under section 163(j), canceled debt, a terminated or revoked qualified subchapter S subsidiary election, Forms 1099, Qualified Opportunity Funds and digital assets; question 17 is reserved. If both conditions in question 11 apply, the corporation does not have to complete Schedules L and M-1.
Complete Schedule K (lines 1 to 18)
Schedule K, on pages 3 and 4, gives the totals of all shareholders' shares of income, deductions, credits and other items, and every corporation filing the return completes it. Line 1 is ordinary business income from page 1, line 22; lines 2 to 10 are other income, lines 11 to 12e deductions, lines 13a to 13g credits, lines 14a and 14b international items (Schedule K-2), lines 15a to 15f alternative minimum tax items, lines 16a to 16f items affecting shareholder basis, and lines 17a to 17d other information. Line 18 reconciles income: combine lines 1 through 10, then subtract lines 11 through 12e and line 16f. Each shareholder's share is reported on a separate Schedule K-1 (Form 1120-S).
Complete Schedules L, M-1 and M-2 (pages 4 and 5)
Schedule L is the balance sheet per books at the beginning and end of the tax year; line 15, column (d), is the total assets figure for item F. Schedule M-1 reconciles net income per books with income on Schedule K, line 18. A corporation with total assets of $10 million or more on the last day of the tax year must file Schedule M-3 (Form 1120-S); the instructions explain when it may still complete Schedule M-1 in place of parts of Schedule M-3. Schedules L and M-1 can be left blank if the answer to Schedule B, question 11, is Yes. Schedule M-2 tracks the accumulated adjustments account, shareholders' undistributed taxable income previously taxed, accumulated earnings and profits, and the other adjustments account from the start to the end of the year.
After you fill it out
The return is filed with the IRS, with a copy of each shareholder's Schedule K-1 and any other schedules and forms it needs attached after page 5, in the order the instructions give. It can be filed on paper or through IRS e-file, and some corporations are required to e-file; for a paper return, the address depends on where the corporation's principal business is located and, for some states, on its total assets, so check the filing address in the IRS instructions. Give each shareholder their Schedule K-1, and pay any amount owed on line 26 electronically as described on the IRS payments page.
Signing: The instructions say the return must be signed and dated by the president, vice president, treasurer, assistant treasurer, chief accounting officer or another officer authorized to sign, or by the receiver, trustee or assignee filing for the corporation. A paid preparer also signs and may use a rubber stamp, mechanical device or software; for the officer's signature, follow the IRS instructions for the way the return is filed.
Watch out for
- Do not file Form 1120-S unless the corporation has filed Form 2553 to elect S status or is attaching it, and do not file it for any tax year before the election takes effect.
- A corporation that files 10 or more returns of any type during the calendar year, counting income tax, employment tax, excise tax and information returns, is required to e-file Form 1120-S unless it has a waiver or an exemption from the IRS.
- This is the 2025 form, for calendar year 2025 and for fiscal years that begin in 2025 and end in 2026. Forms for other years are listed under "All Form 1120-S revisions" on the IRS About Form 1120-S page.
- Tax due on line 26 must be paid electronically, generally by the original due date of the return. An extension of time to file does not extend the time to pay.
Questions about Form 1120-S
Who has to file Form 1120-S?
A corporation or other entity files it when it elected to be an S corporation on Form 2553, the IRS accepted the election, and the election is still in effect. Once made, the election stays in effect until it is terminated, for example when it is revoked or when the corporation no longer meets the definition of a small business corporation.
Does the S corporation pay tax on its income?
Shareholders are taxed on their shares of the corporation's income, whether or not it is distributed to them. The corporation itself is liable for the taxes on page 1, lines 23a through 23c, such as the excess net passive income tax and the built-in gains tax from Schedule D (Form 1120-S).
What do I do with the Schedules K-1?
Schedule K-1 (Form 1120-S) is a separate form showing each shareholder's share. Attach a copy of each one to the Form 1120-S filed with the IRS, keep a copy for the corporation's records, and give each shareholder their copy along with the shareholder's instructions for Schedule K-1.
How does the corporation get more time to file?
File Form 7004 to ask for an automatic extension, generally by the regular due date of the return. The extension is for filing only; any tax due is generally still payable by the original due date.
How do I correct a return that was already filed?
File an amended Form 1120-S with box H(4), Amended return, checked, and attach a statement giving the line number of each changed item, the corrected amount or treatment, and the reason for the change. If a shareholder's Schedule K-1 is wrong, file an amended K-1 with the amended return, check its "Amended K-1" box, and give that shareholder a copy.
Official information
Page text last reviewed November 7, 2026.