Fill Out IRS Form 1120-S Online
U.S. Income Tax Return for an S Corporation
Internal Revenue Service
The annual federal income tax return filed by S corporations.
Reviewed July 2026
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IRS Form 1120-S, U.S. Income Tax Return for an S Corporation, is the annual return filed by corporations and LLCs that have a valid S election in effect. It reports the company's income, gains, losses, deductions, and credits, which pass through to shareholders on Schedule K-1 rather than being taxed at the corporate level in most cases.
You can fill out Form 1120-S in the Universal PDF editor, complete the return and the K-1 for each shareholder, and download the finished PDFs for your records or for review with your tax preparer.
What is Form 1120-S used for
Form 1120-S covers any tax year during which an S election made on Form 2553 is in effect. Like a partnership return, it is primarily informational: ordinary business income flows to Schedule K and then to each shareholder's K-1 in proportion to stock ownership.
Supporting schedules include Schedule B (other information), Schedule K (shareholder totals), Schedule L (balance sheet), Schedules M-1 and M-2 (book-to-tax reconciliation and the accumulated adjustments account), and Schedules K-2 and K-3 for shareholders with international tax items.
Who files Form 1120-S
Form 1120-S is filed by:
- Domestic corporations whose S election has been accepted by the IRS and remains in effect.
- LLCs that elected S corporation treatment.
- The corporation must also furnish a Schedule K-1 to every person who was a shareholder at any point during the year.
How to fill out Form 1120-S
Page 1 reports ordinary trade or business income and deductions, including officer compensation, which the IRS watches closely because S corporation shareholder-employees must pay themselves reasonable wages before taking distributions.
Schedule K aggregates the items that pass through, and each shareholder's K-1 allocates them by ownership percentage. Complete Schedules L, M-1, and M-2 when required, and confirm the election information at the top of the form, including the effective date of the S election, matches your IRS acceptance letter.
Deadlines and extensions
Form 1120-S is due by the 15th day of the third month after the end of the tax year, March 15 for calendar-year S corporations. Schedule K-1 copies must be furnished to shareholders by the same date so they can prepare their individual returns.
Form 7004 provides an automatic six-month extension, moving a calendar-year deadline to September 15. Late filing penalties accrue per shareholder, per month, so file the extension even if the return is almost ready.
Frequently asked questions
The 15th day of the third month after the tax year ends, March 15 for calendar-year filers. Form 7004 extends the filing deadline by six months.
Generally no at the federal entity level; income passes through to shareholders. A few entity-level taxes can apply in special cases, such as built-in gains for corporations that converted from C status.
Yes. Form 1120-S is only for tax years covered by a valid S election made on Form 2553 and accepted by the IRS.
The statement each shareholder receives showing their share of the corporation's income, deductions, and credits, which they report on their personal return.
Yes. Shareholders who work in the business must receive reasonable compensation reported as wages before profit distributions, an area the IRS actively examines. A tax professional can help set a defensible amount.
Filing 1120-S without a valid election causes processing problems. Confirm acceptance with the IRS first; late election relief may be available through the procedures in the Form 2553 instructions.
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