When Are C Corp Extensions Due? Form 7004, Deadlines, Penalties

The C corp extension deadline falls on the same day as the original Form 1120 return: the 15th day of the fourth month after the tax year ends. For a calendar-year corporation, that means Form 7004 must reach the IRS by April 15. Filing it on time pushes the return deadline out six months, but the tax you owe is still due on that original date.

When the Extension Request Is Due

The extension deadline tracks the original filing deadline exactly. Miss the original due date and you miss the extension window with it.¹

Calendar-year C corporations (tax year ending December 31): file Form 7004 by April 15.
Fiscal-year C corporations: file by the 15th day of the fourth month after year-end. A March 31 year-end means a July 15 deadline.
June 30 fiscal-year corporations, tax year beginning before January 1, 2026: file by September 15, following the older third-month rule.²

The June 30 exception is on its way out. For tax years beginning on or after January 1, 2026, June 30 filers move to the standard fourth-month deadline. The first affected fiscal year is one starting July 1, 2026 and ending June 30, 2027, with an original due date of October 15, 2027.²

When a deadline falls on a Saturday, Sunday, or federal holiday, it moves to the next business day.³

How to File Form 7004

The extension is automatic. There is no approval process, no written justification, and no waiting period. File a complete Form 7004 on or before the original due date and the extension is granted.¹

The form asks for basic information: the corporation’s name and EIN, the tax year dates, the return being extended (Form 1120), and a tentative tax calculation. That calculation has three lines: total expected tax for the year, total payments and credits already made, and the balance due. No narrative, no supporting schedules.¹

The balance due shown on Form 7004 must be paid with the filing. Submitting a zero balance when the corporation clearly owes tax invites penalties and interest.

The New Filing Deadline After Extension

The standard extension is six months from the original due date. Calendar-year C corporations move from April 15 to October 15.¹

June 30 fiscal-year filers still in the transition get a seven-month extension rather than six. A corporation with a fiscal year ending June 30, 2026 (which began July 1, 2025) has an original deadline of September 15, 2026, and a seven-month extension pushes that to April 15, 2027.⁴ Once the transition takes full effect for tax years beginning in 2026, June 30 filers get the same six-month extension as everyone else.¹

Payment Is Still Due at the Original Deadline

This is the point that catches corporations off guard. Form 7004 extends the time to file, not the time to pay. The full estimated tax liability is due by the original due date, and filing Form 7004 without paying what you owe does not protect you from late-payment penalties or interest.¹

The federal corporate tax rate is a flat 21%, so a tentative liability is usually straightforward. Estimate taxable income, apply 21%, and subtract quarterly estimated payments already made and any credits. Quarterly installments during the year directly reduce the balance shown on Form 7004; a corporation that kept up may owe little or nothing at extension time.

If the estimate falls short and tax remains owed when Form 1120 is eventually filed, interest runs on the shortfall from the original due date forward. For the first quarter of 2026, the IRS charges 7% on corporate underpayments; for the second quarter beginning April 1, the rate drops to 6%.⁵ Large corporate underpayments, generally where the shortfall exceeds $100,000, get an additional 2 percentage points above the standard rate.⁶

You can avoid the failure-to-pay penalty during the extension period by paying at least 90% of the actual liability by the original due date and settling the balance when you file.⁷ Interest still accrues on that remaining balance, but the penalty itself does not apply.

Penalties for Missing the Deadline

The IRS runs two separate penalties, and they can stack.

Failure to File

If Form 1120 is not filed by the extended deadline, the penalty is 5% of the unpaid tax for each month or partial month the return is late, capped at 25%.⁸ A return more than 60 days late triggers a minimum penalty of $525 or 100% of the unpaid tax, whichever is smaller.⁹

Failure to Pay

When tax remains unpaid after the original due date, the penalty is 0.5% of the unpaid balance per month, also capped at 25%.⁸ The rate jumps to 1% per month if the IRS issues a notice of intent to levy and the tax remains unpaid 10 days later.¹⁰

How They Combine

When both penalties run at the same time, the failure-to-file penalty is reduced by the failure-to-pay penalty for overlapping months. A corporation owing both pays a combined 5% per month (not 5.5%) for the first five months, then 0.5% per month for the failure-to-pay penalty alone until that one also maxes out at 25%.⁹ Interest compounds daily from the original due date on top of everything.

Penalty Relief If Things Go Wrong

Penalties are not always the final word. Two main routes exist to get them reduced or removed.

First-Time Penalty Abatement

If your corporation has a clean compliance record for the three tax years before the penalty year, you can request first-time penalty abatement. Clean means all required returns filed on time, all tax due paid, and no penalties assessed, or any prior penalty removed for a reason other than this same relief.¹¹ It covers the failure-to-file, failure-to-pay, and failure-to-deposit penalties, and you can request it by phone, by letter, or in response to a penalty notice.

Reasonable Cause

Without a clean three-year record, you can still seek relief by showing the failure resulted from reasonable cause rather than willful neglect. The statute builds this exception into the penalty provisions directly.⁸ Circumstances that can qualify include natural disasters, serious illness or death of the person responsible for the corporation’s tax filings, inability to access necessary records, and unavoidable postal delays. Lack of funds by itself does not qualify unless it amounts to genuine economic hardship and you can show you explored other options for payment.

Documentation matters. The IRS evaluates reasonable-cause claims on the specific facts, so attaching medical statements, insurance claims, or disaster declarations strengthens a request compared to a bare assertion.

State Extensions Are Separate

Form 7004 covers your federal return only. State corporate income tax extensions are a separate obligation, and the rules vary. Some states honor the federal extension automatically; others require their own form and independent payment. A handful use different extension lengths or different original deadlines. Because state penalties can mirror the federal ones, check your state’s rules directly rather than assuming Form 7004 covers everything.

1
Internal Revenue Service. Instructions for Form 7004 – Application for Automatic Extension of Time to File Certain Business Income Tax, Information, and Other Returns
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eCFR. 26 CFR 1.6072-2 – Time for Filing Returns of Corporations
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Internal Revenue Service. Starting or Ending a Business 3
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Internal Revenue Service. Publication 509, Tax Calendars
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Internal Revenue Service. Quarterly Interest Rates
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Internal Revenue Service. Internal Revenue Bulletin 2026-8
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Internal Revenue Service. Avoiding Penalties and the Tax Gap
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Office of the Law Revision Counsel. 26 U.S. Code 6651 – Failure to File Tax Return or to Pay Tax
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Internal Revenue Service. Failure to File Penalty
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Internal Revenue Service. Topic No. 653, IRS Notices and Bills, Penalties and Interest Charges
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Internal Revenue Service. Administrative Penalty Relief