An ordinary calendar-year C corporation filing its 2025 federal return was generally required to file Form 1120 and pay tax due by April 15, 2026. A timely, valid Form 7004 generally extends the filing deadline to October 15, 2026, but not the regular payment deadline. Calendar-year corporate estimated-tax installments for 2026 are generally due April 15, June 15, September 15, and December 15, 2026 when the corporation is required to pay estimates.
What is the 2026 Form 1120 deadline?
For an ordinary calendar-year C corporation filing its 2025 return, the federal Form 1120 deadline was April 15, 2026. A timely, valid Form 7004 generally provides a six-month filing extension to October 15, 2026.
The extension changes the filing deadline, not the year shown on the return. It also does not convert a calendar-year rule into the date for a fiscal-year, short-year, initial, final, foreign, or consolidated return.
Does a Form 7004 extension delay the tax payment?
Generally, no. Form 7004 extends time to file, not time to pay. A calendar-year C corporation generally must estimate and pay the balance due by the regular April 15, 2026 deadline even if the return will be filed by October 15.
Interest can apply to tax paid after the regular due date, and late-payment consequences depend on the amount, timing, extension information, and available relief. Keep the extension acceptance and payment confirmations with the return records.
What are the 2026 C corporation estimated-tax dates?
A calendar-year corporation that is required to make federal estimated-tax payments generally uses four installment dates during 2026. The amount and method can depend on expected tax, prior-year facts, annualized income, seasonal income, and other corporate tax rules.
- April 15, 2026
- June 15, 2026
- September 15, 2026
- December 15, 2026
Fiscal-year and June 30 year-end corporations use different rules
A corporation generally files by the 15th day of the fourth month after its tax year ends. A corporation with a fiscal year ending June 30 is subject to a special rule that generally uses the 15th day of the third month after year-end, and the extension period can differ for certain years.
Short-year, dissolved, newly formed, foreign, and consolidated corporations may also require a separate deadline analysis. Use the entity’s actual tax-year ending date and return type rather than copying the calendar-year dates.
What if the corporation missed April 15?
Confirm whether Form 1120 or Form 7004 was accepted, whether a payment was made, and whether a specific disaster-relief notice or another exception applies. Do not assume that an extension filed after April 15 is valid or that an extension eliminated the payment deadline.
If the return is late, bring the records current and quantify the unpaid balance as soon as possible. Filing, payment, estimates, payroll, information returns, and state obligations should be reviewed separately.
State corporate deadlines may not follow the federal extension
States can impose separate income, franchise, minimum, estimated, extension, and payment requirements. Some recognize a federal extension only if a payment or state form is timely; others use different dates or rules.
IRS disaster relief can postpone specific federal deadlines for eligible affected taxpayers, but the covered locations, forms, payments, and periods vary. State disaster relief must also be checked separately.
Records to gather for an extended or late Form 1120
- The prior Form 1120, state returns, extension acceptance, and payment confirmations
- Tax-ready financial statements, general ledger, trial balance, and reconciliations
- Payroll and officer-compensation reports
- Shareholder contributions, distributions, loans, and equity changes
- Fixed assets, depreciation, estimated payments, credits, and major transactions
- State activity, ownership changes, and any information-return requirements