When is Form 1120 due?

A C corporation generally must file Form 1120 by the 15th day of the 4th month after its tax year ends. For a calendar-year 2026 corporation, that is April 15, 2027. Form 7004 gives an automatic 6-month extension of time to file, to October 15, but it does not extend the time to pay.

What is the federal corporate income tax rate?

The federal income tax on C corporations is a flat 21% of taxable income under Internal Revenue Code section 11(b). State corporate income or franchise tax is figured separately in each state where the corporation is taxable.

Does a C corporation have to make estimated tax payments?

Yes, if it expects its total tax for the year, less applicable credits, to be $500 or more. Underpaying estimated tax can lead to a penalty, so payments should be planned around expected income during the year.

What are the corporate income tax rates in DC, Virginia and Maryland?

DC’s corporation franchise tax on Form D-20 is 8.25%, Virginia’s corporation income tax on Form 500 is 6%, and Maryland’s corporation income tax on Form 500 is 8.25%. Each applies to the income apportioned to that jurisdiction.

Does a Form 7004 extension give more time to pay?

No. Form 7004 extends only the time to file. Any tax owed is still due by the original due date of the return, and interest and penalties can apply to unpaid amounts after that date.

What changed for C corporations with a June 30 year end?

C corporations with tax years ending June 30 and beginning before January 1, 2026 were eligible for an automatic 7-month extension. For tax years beginning in 2026, the automatic extension period is 6 months, the same as other corporations.

CPA for C Corporation Tax Returns (Form 1120)

What Form 1120 covers

Form 1120 reports a C corporation’s income, deductions, credits and tax for the year. Unlike an S corporation or partnership, the corporation pays federal income tax itself at a flat 21% of taxable income. Dividends paid to shareholders are then taxed again on the shareholders’ returns.

Due dates and extensions

Original due date: the 15th day of the 4th month after year end, which is April 15, 2027 for calendar-year 2026.
Extension: Form 7004 gives an automatic 6-month extension of time to file, to October 15 for a calendar-year corporation.
Payment: Form 7004 does not extend the time to pay. Estimate the tax and pay it by the original due date.
June 30 year ends: corporations with years ending June 30 that began before January 1, 2026 could get a 7-month extension. For tax years beginning in 2026, the extension is 6 months.

Estimated tax

A corporation must make installment payments of estimated tax if it expects its total tax for the year, less credits, to be $500 or more. We project income during the year and adjust the payments as results change, so the corporation is not paying too much early or facing an underpayment penalty later. See year-end tax planning for businesses.

State corporate returns in DC, Virginia and Maryland

District of Columbia: corporations doing business in DC file Form D-20. The corporation franchise tax rate is 8.25%, with a minimum tax of $250, or $1,000 when DC gross receipts exceed $1 million. See DC business franchise taxes.
Virginia: corporations file Form 500. The tax is 6% of Virginia taxable income, due the 15th day of the 4th month after year end.
Maryland: corporations file Form 500. The rate is a flat 8.25% of Maryland taxable income.

A corporation with activity in more than one of these places generally apportions its income among them. See multi-state nexus for small businesses.

How we work

We review the books and prior returns, prepare the federal and state returns together, plan estimated payments for the coming year and talk through choices such as salary versus dividends for owner-employees. Our fees are transparent and fair, quoted upfront, in writing.

Form 1120 at a glance

Item	Rule
Due date	15th day of the 4th month after year end (April 15, 2027 for calendar-year 2026)
Extension	Form 7004: automatic 6 months to file; tax still due on the original date
Federal rate	21% of taxable income
Estimated tax	Required if expected tax is $500 or more
DC	Form D-20, 8.25%
Virginia	Form 500, 6%
Maryland	Form 500, 8.25%

Expert CPAs. Personal attention.

Need a CPA for your C corporation? We prepare Form 1120 and your DC, Virginia and Maryland corporate returns, and plan estimated payments for the year ahead.

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Frequently asked questions

Sources

General information as of October 4, 2026. Tax rules change; talk to a CPA about your situation.

CPA for C corporation tax returns (Form 1120)

When is a C corporation tax return due?