Business Tax Extensions

C Corporation Tax Extension: Form 7004 for Form 1120

Six extra months to file the corporate return, granted automatically — as long as Form 7004 goes in by April 15 and the estimated tax goes with it. Here is the deadline math, the right form code, and the payment rule that trips corporations up.

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Quick Answer

A C corporation extends Form 1120 by filing Form 7004 with form code 12 by April 15, 2026 (calendar-year 2025 returns). The extension is automatic and adds 6 months, to October 15, 2026. The corporation’s estimated tax must still be paid by April 15 — the extension moves only the paperwork.

The payment rule is the whole game

Unlike pass-through entities, a C corporation owes tax at the entity level — which makes the file-versus-pay distinction expensive to misread. Lines 6–8 of Form 7004 ask for the tentative total tax, payments and credits already made, and the balance due. That balance is due with the extension. A corporation that extends and pays nothing does avoid the 5%-per-month failure-to-file penalty, but interest and the 0.5%-per-month failure-to-pay penalty run on the unpaid tax from April onward. When the estimate is uncertain, paying slightly high beats paying low: overpayments return with the October filing.

Deadlines by year end

Form 1120 is due the 15th day of the 4th month after the corporation’s year ends, and Form 7004 extends it 6 months from that date. Calendar-year 2025: due April 15, 2026, extended to October 15, 2026. A corporation with a September 30 year end is due January 15 and extends to July 15, and so on. The one historical exception — June 30 year ends, which received 7 months — ends with tax years beginning in 2026, when the standard six months applies to them too.

Getting the details right

  • Use the exact registered name and EIN. Name-control mismatches are the most common e-file rejection; the IRS matches the first characters of the legal name against its records.
  • Variant returns use their own codes. 1120-F, 1120-REIT, 1120-RIC, 1120-PC, 1120-POL and others each have a distinct code on the Form 7004 code list — code 12 is for the standard Form 1120 only.
  • Consolidated groups: the common parent files one Form 7004, checks the line 3 box, and attaches the member statement.
  • States are separate. Many states honor or mirror the federal extension; several require their own form or a state payment by the original deadline. Check every state where the corporation files.

Extend Form 1120 in minutes

E-file Form 7004 through the IRS MeF system and keep the acknowledgment as proof of timely filing.

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C corp extension FAQs

When is the C corp extension deadline in 2026?
Form 7004 must be filed by the regular Form 1120 due date: the 15th day of the 4th month after the tax year ends — April 15, 2026 for calendar-year 2025 returns. The extension is automatic and runs six months, to October 15, 2026.
Which form code does a C corporation use on Form 7004?
Code 12 — the Form 1120 entry on line 1 of Form 7004 (Rev. December 2025). Specialized 1120-series returns have their own codes (for example, 1120-F foreign corporations are code 15 and 1120-REIT is code 23), so a corporation filing a variant should use the variant’s code, not 12.
Does the extension delay the corporate tax payment?
No. Form 7004 extends the time to file, never the time to pay. The corporation must estimate its total tax for the year on Form 7004 and pay any balance due by the original April deadline. Unpaid amounts accrue interest and can accrue a failure-to-pay penalty from that date, extension or not.
What about fiscal-year corporations?
The same rules apply, measured from the fiscal year end: Form 1120 is due the 15th day of the 4th month after year end, and Form 7004 extends it six months. One historical wrinkle: corporations with a June 30 year end received a 7-month extension for tax years beginning before January 1, 2026; for tax years beginning in 2026 and later, they get the standard six months.
Does filing an extension increase audit risk?
There is no IRS guidance or credible evidence that a properly filed extension raises audit risk. Extensions are routine — millions are filed each year — and a complete, accurate return filed in October is a far better position than a rushed return filed in April and amended later.

Related guides: Form 7004 overview, every Form 7004 code, late-filing penalties explained.

Disclaimer: Deadlines shift with weekends and holidays and rules change; verify current dates and codes in the IRS Form 7004 instructions. This page is general information, not tax advice. TaxFilingCenter is an IRS-authorized e-file provider and does not provide legal or tax advice.

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