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Official form guide
Form 1120S: U.S. Income Tax Return for an S Corporation
IRS Form 1120-S is the U.S. Income Tax Return for an S Corporation, used to report income, gains, losses, deductions, credits, and other information for a tax year covered by an S election. Calendar-year corporations must file by March 16, 2026 (March 15 falls on Sunday). Failure to file on time may incur a minimum penalty of $525 for returns required to be filed in 2026.
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IRS Form 1120S - U.S. Income Tax Return for an S Corporation
IRS Form 1120-S is the U.S. Income Tax Return for an S Corporation, used to report income, gains, losses, deductions, credits, and other information for a tax year covered by an S election. Calendar-year corporations must file by March 16, 2026 (March 15 falls on Sunday). Failure to file on time may incur a minimum penalty of $525 for returns required to be filed in 2026.
Risk Radar
Scan points- 1Missing the March 16, 2026 deadline for calendar-year S corporations triggers a minimum $525 penalty.
- 2Filing after the due date without an extension, incurring a minimum $525 penalty.
- 3Using a private delivery service to mail to an IRS P.O. box address.
- 4Failing to attach supporting statements in the same order as the schedules they support.
- 5Omitting the corporation's name and EIN on each supporting statement or attachment.
Plain English
This form is how an S corporation tells the IRS what it earned, spent, and owes for the year. It reports the company's income, deductions, and credits, and shows how those amounts are passed to shareholders. The corporation must file it by the due date and pay any tax owed.
Submission Date
- Filing date: 2026-01-30 15:10:36
- Preparation window: collect IDs, supporting records, and signatures in advance.
- Final review: verify names, dates, and required fields before submission.
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What this form is for
- Use this form when the corporation has an accepted S corporation election in effect for the tax year and needs to report income, gains, losses, deductions, credits, and other information.
- Do not use it when the S corporation election has not been accepted or is not in effect, or for any tax year before the election takes effect.
- Check Form 2553 instead when the corporation has not yet elected S corporation status and needs to make the election.
Form selector
Use this form or another form?
Making an S corporation election
Form 1120-S cannot be filed until the election is accepted by the IRS
✓ Confirm IRS acceptance before filing Form 1120-S
Specified domestic corporation with foreign financial assets
Additional reporting required if asset value meets threshold
✓ Review Instructions for Form 8938 for thresholds and exceptions
Requesting an e-file waiver for reasons other than religious belief
Must obtain waiver before electronically filing
✓ Contact e-Help Desk at 866-255-0654 or fax to 877-477-0575
Deadline or filing window
The filing deadline is the 15th day of the 3rd month after the end of the S corporation's tax year. For a calendar-year corporation, the due date is March 16, 2026 (since March 15, 2026 is a Sunday). A dissolved corporation must file by the 15th day of the 3rd month after dissolution. An automatic extension of time to file can be obtained by filing Form 7004 by the regular due date.
Checklist
What you need before filling it out
When To File
Tax year end date · Instructions p.3
Who Must File
Accepted Form 2553 · Instructions p.2
Tax Payments
Full payment by due date · Instructions p.4
Supporting statements and attachments
Proper order, totals, name and EIN on each · Instructions p.4
Section 336(e) election
Election statement attached to Form 1120-S · Instructions p.1
Domestic research expenditures (section 174A)
Amounts paid or incurred after 2024 · Instructions p.1
Conservation contribution
Limit of 2.5 times sum of members' relevant basis · Instructions p.1
Penalties for intentional disregard of information reporting
Correct information required · Instructions p.5
Before you submit
- 1Confirm the S election is in effect for this tax year and that Form 2553 was accepted.
- 2Verify the tax year end date and filing deadline (15th day of 3rd month after year end).
- 3Complete all required schedules (e.g., Schedule K-1, Sch. M-3 if box C checked).
- 4Attach Form 2553 if the election is being made for this tax year and not previously filed.
- 5Enter correct EIN, business name, address, and activity code.
- 6Calculate total assets and enter in box F; ensure consistency with balance sheet.
- 7Sign the return with the authorized officer's signature and date.
- 8Include preparer's signature and PTIN if a paid preparer.
- 9If filing electronically, ensure e-file waiver if needed; otherwise mail to correct IRS address.
- 10Keep a copy of the return and all attachments for your records.
- 11Check for any reportable transactions and attach Form 8886 if required.
- 12Review the entire return for accuracy to avoid penalties.
How to file this form
- 1Gather all financial records, prior year returns, and S election confirmation.
- 2Complete Form 1120-S with all required schedules and attachments.
- 3Attach Form 2553 if the S election is being made for this tax year and not previously filed.
- 4Review the return for completeness, accuracy, and proper signatures.
- 5Sign the return with the authorized officer's signature.
- 6Have the preparer sign and include their PTIN.
- 7File the return electronically or mail it to the appropriate IRS address (see Where To File in instructions).
- 8Retain a copy of the filed return and proof of filing (electronic acknowledgment or certified mail receipt).
Known limitations
- 1Do not file for any tax year before the year the S election takes effect.
- 2Not for corporations that have not elected S status or whose election has been terminated.
- 3No federal income tax deduction allowed for conservation contributions made after December 29, 2022, if the contribution exceeds 2.5 times the sum of each ultimate member’s relevant basis.
- 4If a portion of a section 48, 48C, or 48E credit has been transferred under section 6418, do not use this form (see instructions).
- 5The form is only for domestic corporations or other entities that have an accepted S election in effect.
Field map
Compact field-by-field guide
Entity Info
2 items
Full legal name of the corporation and its Employer Identification Number.
Current mailing address and date of incorporation.
Income
3 items
Total revenue from business operations before deducting costs.
Direct costs attributable to producing goods sold by the corporation.
Gross receipts minus cost of goods sold and returns/allowances.
Deductions
1 items
Sum of all business expenses including compensation, rent, interest, taxes, and depreciation.
Tax
2 items
Total income minus total deductions.
Tax calculated on taxable income using the applicable corporate tax rate, minus any credits.
Signatures
1 items
An authorized corporate officer must sign and date the return.
Almost done reviewing the fields?
Fillable formOpen in Editor->This is the 2025 edition of Form 1120-S (revision 20/25). The instructions point to IRS.gov/Form1120S for the latest information and note an increased minimum penalty for failure to file of $525 for returns required to be filed in 2026.
What changed or needs a fresh check
- Edition date — confirm the form revision reads '20 25' on the form and instructions.
- Fee — no filing fee is required; not stated in the official source.
- Mailing address — not provided in the excerpt; obtain the current IRS address for Form 1120-S from IRS.gov/Form1120S.
- Signature — ensure the return is signed by an authorized officer and the preparer includes their PTIN.
- Electronic filing — check if an e-file waiver is needed; if exempt, write 'Religious Exemption' at top of page 1.
- Penalty — be aware of the minimum $525 penalty for late filing for returns required to be filed in 2026.
Quick Facts
Downloads
After you file
- 1Retain a copy of the filed return and all supporting documents for at least 3 years.
- 2Monitor for IRS acceptance or rejection of electronic filing; if mailed, use certified mail with return receipt.
- 3Distribute Schedule K-1 to each shareholder by the due date of the return.
- 4Pay any tax due (if any) with the return or via electronic payment; S corporations generally do not pay income tax but may owe other taxes.
- 5If an error is discovered, file an amended Form 1120-S (use the version for the year being amended) — not stated in official source; consult IRS.gov for guidance.
- 6Keep records of the S election and acceptance letter for future years.
Sources
- SRCInstructions p.1 — The form is for reporting income, gains, losses, deductions, credits of an S corporation.
- SRCInstructions p.2 — Who Must File: corporation that elected S status and IRS accepted.
- SRCInstructions p.3 — Filing deadline: 15th day of 3rd month after tax year end.
- SRCInstructions p.1 — Minimum penalty for failure to file increased to $525 for returns due in 2026.
- SRCInstructions p.3 — Exemptions from e-file: write 'Religious Exemption' at top of Form 1120-S.
- SRCForm p.1 — Do not file unless Form 2553 filed or attached.
- SRCInstructions p.7 — Penalties for failure to file Form 8886 for reportable transactions.
- SRCInstructions p.2 — How to get forms: IRS.gov/Forms.
- SRCInstructions p.3 — Address for e-file waiver request: Mail Stop 1057, Ogden, UT 84404.
- SRCInstructions p.1 — No deduction for conservation contributions exceeding 2.5 times basis after Dec 29, 2022.
Common confusion points
When is the filing deadline?
Form 1120-S is due by the 15th day of the 3rd month after the end of the tax year
→ Check your tax year end date and count forward 2.5 months
Do I need to file Form 1120-S before my S election is accepted?
No, you must wait until the election takes effect
→ Do not file until you receive acceptance; call 800-829-4933 if no response in 2 months (5 months if box Q1 checked)
What if I need an e-file waiver?
Two options: religious exemption (write on return) or formal waiver request
→ For religious exemption write 'Religious Exemption' at top of page 1; for other waivers mail/fax Form 1120 e-file Waiver Request
Where do I mail the return?
Address depends on principal business location and total assets
→ Use the address table in Instructions p.4 based on location and asset amount
Do I need to attach Form 8938?
Only if the corporation is a specified domestic entity and foreign financial assets meet the reporting threshold
→ Review Instructions for Form 8938 to determine if filing is required
What is the penalty for intentional disregard of information reporting?
$340 per item, increased to $680 if intentional, or 10% of aggregate amount
→ Ensure all required information is reported correctly and timely
Can I deduct conservation contributions?
Deduction is limited if contribution exceeds 2.5 times the sum of each ultimate member's relevant basis
→ Calculate the relevant basis before claiming a deduction
How do I handle a section 336(e) election?
File Form 1120-S with the election statement attached by the 15th day of the 3rd month after the qualified stock disposition
→ Attach the statement and note the special deadline; see When To File
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Questions about IRS Form 1120S
What is IRS Form 1120S used for?
This form is how an S corporation tells the IRS what it earned, spent, and owes for the year. It reports the company's income, deductions, and credits, and shows how those amounts are passed to shareholders. The corporation must file it by the due date and pay any tax owed.
Who must file IRS Form 1120S?
A domestic corporation or other entity that has made an election to be an S corporation for the tax year must file Form 1120-S. If the election is terminated during the year, the S corporation files for its short year.
What information does IRS Form 1120S require?
The form collects the corporation's income, gains, losses, deductions, credits, and other information. It includes a balance sheet and shareholder information, with supporting statements attached in order.
When is IRS Form 1120S due?
Generally, an S corporation must file 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 (March 15 falls on Sunday). An extension of time to file can be requested using Form 7004.
Where do I file IRS Form 1120S?
File the return at the IRS address listed in the instructions based on the corporation's principal business location and total assets at the end of the tax year (Form 1120-S, page 1, item F). The specific address depends on these factors; see the instructions for the correct address.
How do I complete IRS Form 1120S?
Complete all applicable schedules and lines on Form 1120-S, including the income statement and balance sheet. Attach supporting statements in the same order as the schedules they support, with the corporation's name and EIN on each. The return must be signed and dated by an authorized officer (president, vice president, treasurer, assistant treasurer, or chief accounting officer).
What happens if IRS Form 1120S is filed incorrectly?
Failure to file on time may result in a minimum penalty of $525 for returns required to be filed in 2026, plus interest on any unpaid tax from the due date. Interest is also charged on penalties for late filing, negligence, or fraud.
When is the filing deadline?
Form 1120-S is due by the 15th day of the 3rd month after the end of the tax year Check your tax year end date and count forward 2.5 months
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