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Short answer
A U.S. corporation files a state report every year or two (the date depends on the state) and a federal Form 1120 by the 15th day of the 4th month after its tax year ends: April 15 for a calendar year. A corporation 25% or more foreign-owned attaches Form 5472. If a date falls on a weekend or legal holiday, it moves to the next business day.
How this tool works
State dates come from each state’s report rule. Federal dates follow IRS rules for C corporations with a calendar tax year. Estimated tax payments apply only when the company expects to owe $500 or more for the year.
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Sources
- IRS: About Form 1120
- IRS: Instructions for Form 5472
- Delaware Division of Corporations: Annual Report and Tax Information
Updated October 30, 2026. General information, not legal or tax advice.
Questions founders ask
For a calendar-year C corporation, April 15. For other tax years, the 15th day of the 4th month after the year ends. Form 7004 gives 6 more months to file, but not to pay.
With Form 1120, on the same date. An extension of Form 1120 also extends Form 5472.
Federal deadlines move to the next business day. Many states do the same, but check each state.
A C corporation pays estimated tax in four parts if it expects to owe $500 or more for the year: by the 15th day of the 4th, 6th, 9th and 12th months of its tax year.
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