A Delaware C-corp on a calendar year has about ten dates a year that carry a penalty. Most founders know April 15. Fewer know that March 1 costs $200 plus interest the day after, or that the extension they file in April did not extend the payment.
Here is the year, in order, for a company incorporated in Delaware with a December year end. State dates for wherever you actually operate are added at the end.
January 31: 1099-NEC and W-2
Two filings, same day. Form 1099-NEC goes to every US contractor you paid $600 or more during the prior year, and a copy to the IRS. Form W-2 goes to every employee and to the Social Security Administration.
Your payroll provider almost certainly files the W-2s. The 1099s are yours, and they need a W-9 from each contractor, which is far easier to collect in October than in the last week of January. If you paid a contractor through a payment processor, the processor's 1099-K may cover it; check before you double-report. (The 1099-K reports gross, which is not what landed in your bank.)
March 1: Delaware franchise tax and annual report
Due to the Delaware Division of Corporations: the annual report, a $50 fee, and the franchise tax. The tax calculates two ways, and the notice shows the expensive one. A seed-stage company with 10,000,000 authorised shares sees $85,165 on the notice and owes $400 under the Assumed Par Value method, which the portal recalculates once you enter gross assets and issued shares (run both methods here). Late is a $200 penalty plus 1.5% interest per month. The full arithmetic is in what your Delaware franchise tax actually costs.
April 15: Form 1120 and the first estimated payment
Form 1120, the corporate income tax return, is due the 15th day of the fourth month after year end. It is prepared from the closed books, on whichever basis you keep them. For a December year end that is April 15.
If you are not ready, Form 7004 filed by this date gives an automatic six-month extension to October 15. The extension moves the paperwork, not the payment: tax owed was due April 15 regardless, and the underpayment accrues interest from that date.
The same day, the first quarterly estimated payment is due. Estimated payments are required once you expect to owe $500 or more for the year. A pre-revenue startup with a loss owes nothing and pays nothing; a profitable one pays a quarter of the expected liability.
June 15: second estimated payment
The second instalment. Same rule.
September 15: third estimated payment
The third instalment. If you filed a 7004 in April, this is also a reasonable date to check that the extended return is on track, because the October deadline does not move.
October 15: extended Form 1120
Final deadline for the 1120 if you extended. There is no second extension.
December 15: fourth estimated payment
The last instalment of the year, and the one that is easiest to forget because it lands in the holiday run-up. Companies that turned profitable during the year often discover here that they owed the earlier three too.
The dates that are not on this list
A June 30 fiscal year changes the pattern. Under current law a June year end keeps the older deadline: the return is due September 15 (the third month), and the extension runs seven months rather than six. If your year end is anything other than December, the 1120 is due the 15th of the fourth month after it, and the four estimated payments land in the fourth, sixth, ninth and twelfth months of your fiscal year.
Delaware LLCs (choosing between the two?) are not on this calendar. A Delaware LLC owes a flat $300 annual tax on June 1, with no annual report, and its income is reported on the members' returns or, for a multi-member LLC, on Form 1065 due March 15.
The state you operate in has its own list, and it is the one that catches Delaware companies out. California charges an $800 minimum franchise tax and a Statement of Information. New York, Texas, Washington and most others have an annual report and a minimum tax or fee, some on a fixed date and some on the anniversary of your registration. If you have employees or an office in a state, you are registered there, and its dates apply.
One calendar, your dates
The generic version of this calendar is above. The specific version depends on your entity type, your fiscal year end and every state you are registered in. We built a tool that produces it: vecty.ai/tools/tax-deadline-calendar. Pick the entity, the year end and the state, and it lists the dated items soonest-first with days remaining.
Every date here is the standard deadline. When one falls on a weekend or a federal holiday it rolls to the next business day; the authority's own calendar is the final word.
Common questions
When is Form 1120 due for a calendar-year C-corp?
April 15, the 15th day of the fourth month after year end. Form 7004 filed by that date gives an automatic extension to October 15, but the extension moves the paperwork only: the tax owed was still due on April 15 and accrues interest from that date.
When are corporate estimated tax payments due?
April 15, June 15, September 15 and December 15 for a calendar-year C-corp, which is the 15th of the fourth, sixth, ninth and twelfth months of the tax year. They are required once you expect to owe $500 or more for the year. A pre-revenue company with a loss owes nothing.
What is due on January 31?
Form 1099-NEC to every US contractor you paid $600 or more in the prior year, with a copy to the IRS, and Form W-2 to every employee and to the Social Security Administration. Payroll providers usually file the W-2s; the 1099s are yours and need a W-9 from each contractor.
Tools that go with this
- Startup tax deadline calendar - this calendar for your entity, year end and state, soonest first
- Delaware franchise tax calculator - the March 1 number, both methods
- State franchise tax and annual report calculator (all 50 states) - every other state's annual report and minimum tax
- Entity type advisor: LLC vs C-corp vs S-corp - C-corp vs LLC vs S-corp, which sets the whole calendar