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Federal income tax deadlines for businesses

Which federal return each kind of business files, when it is due, and how far an extension reaches.

For a calendar-year 2026 business, partnership and S corporation returns (Forms 1065 and 1120-S) are due March 15, 2027, and C corporation returns (Form 1120) are due April 15, 2027. Form 7004 extends each by six months, to September 15 or October 15, 2027, but does not extend the time to pay.

Last reviewed September 23, 2026 · Tax year 2026 · Federal and Florida

The due date follows how the business is taxed, which is not always how it was formed. An LLC with two or more members is taxed as a partnership unless it elects otherwise, and an LLC with one member is disregarded, so its owner reports it. If you are unsure which applies, What is my tax classification and what does it mean? covers it.

The 2026 returns

  • Partnership, or LLC with two or more members. Return: Form 1065. Due: March 15, 2027. Extended due: September 15, 2027.
  • S corporation. Return: Form 1120-S. Due: March 15, 2027. Extended due: September 15, 2027.
  • C corporation. Return: Form 1120. Due: April 15, 2027. Extended due: October 15, 2027.
  • Sole proprietor, or LLC with one individual owner. Return: Schedule C (E or F for rental or farm income), filed with the owner's Form 1040. Due: April 15, 2027. Extended due: The owner's personal extension.

These dates are for a business whose tax year is calendar 2026. Partnership and S corporation returns are due the 15th day of the third month after the year ends. C corporation and individual returns are due the 15th day of the fourth month, and a sole proprietor's business is reported on Schedule C with the owner's return.

When a due date falls on a Saturday, Sunday or legal holiday, a return filed the next business day is on time. None of the 2027 dates in the table do. March 15, 2026 was a Sunday, so calendar-year 2025 Forms 1065 and 1120-S were due Monday, March 16, 2026.

Fiscal-year businesses

A business whose year ends in another month counts the same months from its own year end. An illustration: a partnership whose year ends June 30 files by September 15, and a C corporation whose year ends March 31 files by July 15.

C corporations with a June 30 year end are the exception. For a year that began before January 1, 2026, the return was due the 15th day of the third month, and the automatic extension runs seven months instead of six. A June 30 year that begins in 2026 follows the fourth-month rule and the six-month extension.

Extensions

Form 7004 gives an automatic six-month extension to file if it is filed by the return's original due date. For calendar-year 2026 returns that is September 15, 2027 for Forms 1065 and 1120-S, and October 15, 2027 for Form 1120. A Schedule C business has no separate return to extend; the owner extends the Form 1040, as described in Federal income tax deadlines for individuals.

The extension moves the filing date only. Tax due with a corporation's return is still due on the original date. A partnership pays no income tax itself, and an S corporation generally does not; their profit is taxed on the owners' returns, which have their own dates. A C corporation pays its own tax, so its payment date stays April 15 even when the Form 1120 is filed in October. The payment side is in An extension gives you more time to file, not to pay.

Where 2025 stands

Extended calendar-year 2025 Forms 1065 and 1120-S were due September 15, 2026. An extended calendar-year 2025 Form 1120 is due Thursday, October 15, 2026.

Florida

Florida has no personal income tax, so individual owners of a partnership, an S corporation or a sole proprietorship owe Florida no income tax on their share of the profit. A corporation subject to Florida corporate income tax files a separate Florida return, even when no tax is due, on dates set by Florida law, listed in Payroll, sales tax and Florida business deadlines.

Sources

  1. IRC § 6072, time for filing income tax returns
  2. IRC § 6081, extension of time for filing returns
  3. IRC § 7503, time for performance of acts where last day falls on Saturday, Sunday, or legal holiday
  4. IRC § 701, partners, not partnership, subject to tax
  5. IRC § 1363, effect of election on S corporation
  6. Treas. Reg. § 1.6081-2, automatic extension of time to file certain returns filed by partnerships
  7. Treas. Reg. § 1.6081-3, automatic extension of time for filing corporation income tax returns
  8. Treas. Reg. § 301.7701-3, classification of entities that are not corporations
  9. Pub. L. 114-41, § 2006, new due dates for partnership and C corporation returns
  10. IRS, Instructions for Form 1065
  11. IRS, Instructions for Form 1120-S
  12. IRS, Instructions for Form 1120
  13. IRS, Instructions for Form 7004
  14. IRS, Instructions for Schedule C (Form 1040)
  15. Florida Constitution, art. VII, § 5 (no tax on the income of natural persons)
  16. Florida Statutes § 220.222, returns; time and place for filing
  17. Florida Statutes § 220.22, returns; filing requirement

This article is general educational information, not tax, legal, or accounting advice, and does not create a client relationship. Tax law changes and depends on your specific facts. Information is current as of September 23, 2026 for tax year 2026; verify before acting. Consult a qualified CPA, EA, or attorney about your situation.

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