Corporate Tax Deadline 2026
Form 1120 filing, extension and estimated-payment dates for calendar-year C corporations, plus the fiscal-year rule.
March 16
Calendar-year Form 1120-S
April 15
Form 1120 + first estimate
October 15
Extended Form 1120 filing
December 15
Fourth estimated payment
Calendar-year C-corporation dates
| Date | Action | Form |
|---|---|---|
| April 15, 2026 | File the 2025 calendar-year return and pay tax due | Form 1120 |
| April 15, 2026 | Request an automatic six-month filing extension | Form 7004 |
| April 15, June 15, September 15, December 15 | Calendar-year 2026 estimated tax installments | Electronic payment / corporate estimate |
| October 15, 2026 | File an extended calendar-year Form 1120 | Form 1120 |
Fiscal-year rule
Most fiscal-year C corporations file on the 15th day of the fourth month after year end. June 30 year-end corporations have a special filing rule and can receive a seven-month extension in circumstances described by the 2026 IRS calendar and Form 7004 instructions.
Corporate deadline questions
When is the corporate tax deadline in 2026?
A calendar-year C corporation must file Form 1120 and pay tax due by April 15, 2026.
What is the extended corporate tax deadline for 2026?
A timely Form 7004 generally gives a calendar-year C corporation a six-month filing extension to October 15, 2026. The extension does not move the April 15 payment deadline.
How do I extend a corporate tax return?
File Form 7004 by the original Form 1120 due date and make a proper estimate of tax. Pay the expected balance by the original due date because an extension of time to file is not an extension of time to pay.
When is Form 1120 due for a fiscal-year corporation?
Form 1120 is generally due on the 15th day of the fourth month after the tax year ends. A corporation with a June 30 year end follows a special third-month filing rule, and June year-end extension periods can differ.
When are 2026 corporate estimated tax payments due?
For a calendar-year corporation, the 2026 installments fall on April 15, June 15, September 15 and December 15, subject to weekend and legal-holiday adjustments.
Is Form 1120-S due on the same date as Form 1120?
No. A calendar-year S corporation generally files Form 1120-S by March 16, 2026 because March 15 falls on a Sunday. The April 15 date applies to calendar-year C-corporation Form 1120.
Sources
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