Tax Forms Entity Returns Fillable Form 1120-S (2025)

Form 1120-S (2025)

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What is Form 1120-S?

Form 1120-S, U.S. Income Tax Return for an S Corporation, is the annual income tax return that an S corporation files with the IRS. The form above is the 2025 revision (for calendar year 2025 or a tax year beginning in 2025), five pages, OMB No. 1545-0123.

A corporation or other entity must file Form 1120-S if it elected to be an S corporation by filing Form 2553, the IRS accepted the election, and the election remains in effect. The form itself says: do not file it unless the corporation has filed or is attaching Form 2553. Domestic corporations without an S election generally file Form 1120 instead, unless they are exempt or are required or elect to file a special return.

When is Form 1120-S due?

Generally, an S corporation must file Form 1120-S by the 15th day of the 3rd month after the end of its tax year. For calendar-year corporations the 2025 return is due March 16, 2026, because March 15 falls on a Sunday.

To ask for more time to file, submit Form 7004 (automatic extension) by the regular due date of the return. Form 7004 does not extend the time to pay any tax due. S corporations filing 10 or more returns of any type during the calendar year generally must e-file Form 1120-S. Waivers may be requested, and a religious exemption may apply; see the IRS electronic-filing instructions.

How to fill out Form 1120-S

  1. Page 1: identification items A-J (S election effective date, business activity code, EIN, date incorporated, total assets, the Form 2553 question, and the "Check if" boxes in item H), then Income (lines 1a-6), Deductions (lines 7-22) and Tax and Payments (lines 23a-28e, including direct deposit details for a refund).
  2. Pages 2-3: Schedule B, Other Information (accounting method, ownership and the yes/no questions).
  3. Pages 3-4: Schedule K, Shareholders' Pro Rata Share Items, the totals that are then split among the shareholders on their Schedules K-1. Attach a copy of each Schedule K-1 to the return, keep a copy, and give each shareholder a copy.
  4. Page 4: Schedule L, Balance Sheets per Books. Schedule L is not required if the corporation answered "Yes" to Schedule B, question 11 (total receipts and total assets both under $250,000).
  5. Page 5: Schedule M-1 (reconciliation of book income with return income) and Schedule M-2. Schedule M-1 is not required if Schedule B, question 11, is answered "Yes". Corporations with year-end total assets of $10 million or more must file Schedule M-3. For 2025, required M-3 filers with assets below $50 million may complete M-3 Part I and Schedule M-1 instead of M-3 Parts II and III.
  6. Sign and date the return. It must be signed 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 on the corporation's behalf, the fiduciary signs instead.

How to fill out Form 1120-S

Page 1: identification items A-J, then Income (lines 1a-6), Deductions (lines 7-22) and Tax and Payments (lines 23a-28e). Pages 2-3: Schedule B, Other Information. Pages 3-4: Schedule K, Shareholders' Pro Rata Share Items; attach a copy of each Schedule K-1 and give each shareholder a copy. Page 4: Schedule L, Balance Sheets per Books (not required if Schedule B, question 11, is answered "Yes"). Page 5: Schedules M-1 and M-2. M-1 is not required after a "Yes" to Schedule B, question 11. Assets of $10 million or more require M-3; qualifying filers may use M-3 Part I with M-1. See the Schedule M-3 instructions. Sign and date the return as an authorized corporate officer, or as the receiver, trustee or assignee when a fiduciary files for the corporation.

Form Versions

2019 Form 1120-S for 2019 tax year Fill Out Form
2020 Form 1120-S for 2020 tax year Fill Out Form
2021 Form 1120-S for 2021 tax year Fill Out Form
2022 Form 1120-S for 2022 tax year Fill Out Form
2023 Form 1120-S for 2023 tax year Fill Out Form
2024 Form 1120-S for 2024 tax year Fill Out Form

Form 1120-S: frequently asked questions

  • How do I amend Form 1120-S?

    File an amended Form 1120-S and check box H(4), "Amended return", on page 1. Attach a statement that identifies the line number of each amended item, the corrected amount or treatment of the item, and the reason for each change. If the information on any shareholder's Schedule K-1 (or K-3) was incorrect, file an amended Schedule K-1 or K-3 with the amended return, check the "Amended K-1" or "Amended K-3" box on it, and give a copy to that shareholder.

  • How is Form 1120 different from Form 1120-S?

    Form 1120-S is the return of a corporation whose S election is in effect. Domestic corporations that are not exempt and are not required to, and do not elect to, file a special return file Form 1120, U.S. Corporation Income Tax Return.

  • When is Form 1120-S due?

    Generally, by the 15th day of the 3rd month after the end of the corporation's tax year. For calendar-year corporations the 2025 return is due March 16, 2026. An extension of time to file is requested on Form 7004, filed by that date; it does not extend the time to pay any tax due.

  • Where can I find Form 1120-S?

    The current form and instructions are on IRS.gov (irs.gov/Form1120S). On PDFLiner, the 2025 form is the blank above; earlier revisions are listed under Form versions.

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