An S corporation tax return is generally due on the 15th day of the third month after the tax year ends. For most calendar-year S corporations, Form 1120-S is due March 15. If March 15 falls on a weekend or legal holiday, the deadline moves to the next business day.
For the 2025 tax year, the federal deadline was March 16, 2026, because March 15 fell on a Sunday. An S corporation that timely filed Form 7004 had until September 15, 2026, to file its extended return.
S Corporation Tax Deadlines at a Glance
| Tax Situation | Federal Deadline |
|---|---|
| Calendar-year S corporation return for the 2025 tax year | March 16, 2026 |
| Extended 2025 calendar-year return | September 15, 2026 |
| Calendar-year S corporation return for the 2026 tax year | March 15, 2027 |
| Fiscal-year S corporation | 15th day of the third month after the tax year ends |
| Schedule K-1 delivery to shareholders | Same general deadline as Form 1120-S |
What Does an S Corporation File?
An S corporation files Form 1120-S, U.S. Income Tax Return for an S Corporation. The corporation generally reports its income, deductions, credits and other tax information to shareholders through Schedule K-1.
The IRS requires the S corporation to provide Schedule K-1 information by the 15th day of the third month after the end of its tax year.
An S corporation can still owe certain federal taxes, including employment, excise or other entity-level taxes. Any balance shown on the return is generally due by the original filing deadline. An extension gives the corporation more time to file, but not more time to pay.
Does an S Corporation Get an Extension?
Yes. An S corporation can request an automatic six-month filing extension by submitting Form 7004 by the original Form 1120-S deadline. The extension applies to filing the return, not to paying taxes owed.
For a calendar-year S corporation:
- File Form 1120-S by March 15, or the next business day when the deadline falls on a weekend or legal holiday.
- File Form 7004 by that date if the corporation needs more time to file.
- File the extended return by September 15.
- Pay any required tax by the original deadline to reduce interest and penalties.
What About S Corporation Owners' Personal Taxes?
Shareholders generally report their share of S corporation income on their personal tax returns using Schedule K-1. A shareholder's individual federal tax return is usually due April 15, unless the shareholder has a different filing deadline or receives a personal extension.
An S corporation owner may also need to make personal estimated tax payments during the year. Those payments have separate due dates and do not change the corporation's Form 1120-S deadline.
Are Payroll Taxes Due on March 15?
No. Payroll tax deposits, payroll tax returns, state taxes and sales taxes follow separate deadlines. The due dates depend on the corporation's payroll schedule, tax liability and state requirements.
The March 15 deadline primarily applies to the federal Form 1120-S filing and Schedule K-1 reporting. It does not apply to every tax obligation connected with the business.