A corporation that expects to owe at least $500 in federal income tax for the year must make quarterly estimated tax payments to the IRS, and corporation quarterly tax payments are due on the 15th day of the 4th, 6th, 9th, and 12th months of the tax year. Each installment generally equals 25% of the lesser of the current year’s tax or the prior year’s tax, and it has to move electronically. Miss a deadline or underpay, and the penalty runs like interest from the day the money was due, with no reasonable-cause waiver available.
Which Corporations Have to Pay
The trigger is a total tax liability of $500 or more for the year.1Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax There is no application, no exemption to claim. The corporation projects its income, applies the 21% corporate rate, subtracts credits, and if the result reaches $500, quarterly payments are required.
The rule reaches beyond ordinary C-corporations. Tax-exempt organizations with unrelated business income use the same $500 threshold and calculate estimated tax on Form 990-W as an internal worksheet, then report the income annually on Form 990-T.2Internal Revenue Service. Underpayment of Estimated Tax by Corporations Penalty New corporations are covered from the start, with no first-year grace period. Waiting until the annual return to pay in one lump will produce penalties even if the full balance goes in with the return.
The Four Due Dates
For a calendar-year corporation, the installments fall on April 15, June 15, September 15, and December 15. If a due date lands on a weekend or federal holiday, it moves to the next business day.1Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
Fiscal-year corporations follow the same pattern using their own months: the 15th day of the 4th, 6th, 9th, and 12th months of the fiscal year. A corporation whose year begins July 1 owes on October 15, December 15, March 15, and June 15.1Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
One thing to watch: the corporate schedule is not the individual schedule. Individuals get until January 15 of the following year for their fourth-quarter payment. Corporations pay in December, before the tax year even ends.
How Much to Pay Each Quarter
Each installment is 25% of the “required annual payment,” which is the lesser of:1Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
- 100% of the tax shown on the current year’s return, or
- 100% of the tax shown on the prior year’s return, if that return covered a full 12 months and reported some tax.
The prior-year figure is the practical safe harbor. Pay four equal installments totaling last year’s tax and no underpayment penalty applies, even if this year’s actual tax turns out much higher. That protection is what makes growth years manageable.
The prior-year option disappears in two situations: a short prior year (fewer than 12 months) or a prior year with no tax liability, including a year zeroed out by a net operating loss. When the safe harbor is off the table, installments have to be built from a current-year projection.1Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
Form 1120-W used to be the IRS worksheet for this calculation. The 2022 edition was the last; the form is now historical and no longer updated.3Internal Revenue Service. IRS Publication 542 – Corporations The math is unchanged, but corporations now run it against the Form 1120 instructions and their own books rather than a standalone IRS form.
Expected credits reduce the estimate. The research credit and the foreign tax credit are common examples. Two provisions push in the other direction for the largest filers. The Base Erosion and Anti-Abuse Tax applies to multinationals with at least $500 million in gross receipts that make significant deductible payments to related foreign entities. The Corporate Alternative Minimum Tax, enacted by the Inflation Reduction Act of 2022, imposes a 15% minimum tax on adjusted financial statement income for corporations averaging $1 billion or more in book profits over a three-year period. Both feed into the estimated tax calculation for corporations subject to them.
Large Corporations Lose the Prior-Year Safe Harbor
A “large corporation” for these rules is one with taxable income of $1 million or more in any of the three preceding tax years. Large corporations can only rely on the prior-year figure for the first installment. The remaining three must be based on 100% of the current year’s actual tax.1Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
There is also a catch-up. If the first installment used a lower prior-year number, the shortfall against 25% of the current year’s tax is added to the second installment. The savings do not carry through the year.1Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
The $1 million lookback includes the taxable income of any predecessor corporation, so a merger or acquisition can turn a smaller entity into a “large” one under the rule.
Seasonal or Uneven Income
Corporations that earn most of their income late in the year do not have to pay four equal installments built on a full-year projection. The annualized income installment method bases each quarter’s payment on income actually earned through that point in the year, annualized to a full-year figure. An adjusted seasonal installment method is available for businesses with a predictable seasonal pattern.4Internal Revenue Service. Instructions for Form 2220
Either method is elected by completing Schedule A of Form 2220 and attaching it to the annual return. A corporation cannot simply pay less during the year and claim the method later.
How to Send the Payment
Corporate estimated tax payments must go through the Electronic Federal Tax Payment System. Checks and money orders are not accepted for this obligation.5U.S. Department of the Treasury. Electronic Federal Tax Payment System Enrollment requires the EIN and the corporation’s bank information. Once enrolled, the business selects Form 1120, designates the tax period, and schedules the transfer.
To count as timely, a scheduled EFTPS payment must be entered by 8:00 p.m. Eastern Time the day before the due date.5U.S. Department of the Treasury. Electronic Federal Tax Payment System The system issues a confirmation number after each submission. Keep it with the tax records.
If that cutoff has already passed or enrollment isn’t in place, a same-day wire through the corporation’s bank may still deliver the payment on time. The corporation completes the IRS Same-Day Taxpayer Worksheet (one per form and period) and submits it through a financial institution that offers the Federal Tax Collection Service. Bank cutoffs and fees vary.6Internal Revenue Service. Same-Day Wire Federal Tax Payments EFTPS itself will also process a same-day payment of $1 million or less if submitted before 3:00 p.m. Eastern Time on a business day; payments over $1 million must be scheduled at least one calendar day ahead.7U.S. Department of the Treasury. Electronic Federal Tax Payment System Financial Institution Handbook
What Underpayment Costs
The underpayment penalty functions as interest on whatever the corporation should have paid but didn’t, running from the installment due date until the earlier of when the payment is made or the return’s due date. The IRS publishes the applicable rate each quarter. For the second quarter of 2026, the corporate underpayment rate is 6%.8Internal Revenue Service. Quarterly Interest Rates
Each installment period is calculated separately. A later overpayment gets credited to earlier underpaid installments in order, but only from the date the overpayment is actually made. It does not retroactively erase the penalty that already accrued.1Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
Underpayments over $100,000 carry a higher rate. These “large corporate underpayments” are charged the federal short-term rate plus five percentage points instead of three, which produced an 8% rate for the second quarter of 2026.9Office of the Law Revision Counsel. 26 USC 6621 – Determination of Rate of Interest
One feature of this penalty separates it from most others: reasonable cause does not waive it. The narrow exception is a corporation that relied on incorrect written advice from the IRS itself.2Internal Revenue Service. Underpayment of Estimated Tax by Corporations Penalty A miscalculation, an oversight, or a busy quarter is not a defense.
Getting Overpayments Back Quickly
A corporation that has paid in too much does not have to wait for the annual return to see the money. Form 4466 requests a quick refund when the overpayment is at least $500 and at least 10% of the expected tax liability for the year.10Internal Revenue Service. About Form 4466 – Corporation Application for Quick Refund of Overpayment of Estimated Tax
The window is short. Form 4466 has to be filed after the tax year ends, before the corporation files its annual return, and no later than the unextended due date of that return. A filing extension does not extend the Form 4466 deadline.11Internal Revenue Service. Instructions for Form 4466 For a calendar-year corporation, that means filing by April 15 and before Form 1120 goes in. Miss the window, and the refund waits for the return.