IRS Form 2220 is the worksheet a corporation uses to figure the penalty it owes when its quarterly estimated tax payments fell short during the year. The penalty is not a flat charge. It is an interest amount calculated separately for each of the four installments, based on how much was underpaid and how long the shortfall stayed unpaid. The final number moves from Form 2220 to the penalty line of the corporate income tax return.
Which Corporations Have to Run the Calculation
A corporation must make quarterly estimated tax payments whenever it expects total tax for the year, after credits, to be $500 or more. S corporations, tax-exempt organizations subject to unrelated business income tax, and private foundations fall under the same requirement and use Form 2220 to figure any penalty.1Internal Revenue Service. Instructions for Form 2220
Installments are due on the 15th day of the 4th, 6th, 9th, and 12th months of the corporation’s tax year. For a calendar-year filer, that means April 15, June 15, September 15, and December 15, with weekend or holiday dates pushed to the next business day.2Internal Revenue Service. Underpayment of Estimated Tax by Corporations Penalty
The Required Annual Payment
The penalty measures actual deposits against a target called the required annual payment. That target is the lesser of 100 percent of the current year’s tax or 100 percent of the prior year’s tax. The prior-year figure is only available if the prior year was a full 12 months and the return showed some tax liability.3Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
Each quarterly installment is 25 percent of that annual amount. Miss the mark on any due date, and the difference becomes an underpayment for that quarter.
Large Corporation Rule
A large corporation is one that reported taxable income of $1 million or more in any of the three preceding tax years. Only the first installment of a large corporation can be based on the prior year’s tax. Installments two through four must be based on 100 percent of the current year’s expected tax. If the prior-year figure used for the first installment turns out to be below 25 percent of current-year tax, the shortfall has to be made up with the second installment.3Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax
How to Calculate the Penalty
Form 2220 walks the arithmetic through four installments. The math for each is the same.
Find the Underpayment
For each due date, compare what the corporation actually deposited to 25 percent of the required annual payment. The gap is the underpayment for that quarter. If a quarter was paid in full and on time, no penalty applies to that installment no matter what happens later in the year.
Count the Days
The penalty clock runs from the installment due date until the earlier of the date the corporation pays the shortfall or the 15th day of the 4th month after the tax year ends. For a calendar-year corporation, that outer stop is April 15 of the following year.3Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax A late payment made before the next installment due date shortens the period for the earlier quarter’s shortfall.
Apply the Rate
The IRS sets the underpayment interest rate every quarter at the federal short-term rate plus 3 percentage points, compounded daily.4Internal Revenue Service. Topic No. 653 IRS Notices and Bills, Penalties and Interest Charges Large corporate underpayments carry a higher rate of the federal short-term rate plus 5 percentage points on any portion still outstanding after the IRS sends a notice or the return is filed.5Office of the Law Revision Counsel. 26 USC 6621 – Determination of Rate of Interest
For the first half of 2026, the standard corporate underpayment rate is 6 percent. The large corporate rate started 2026 at 9 percent and dropped to 8 percent in Q2.6Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 Because rates change quarterly, a penalty period that crosses a rate change uses each quarter’s rate for the days that fall inside it.
Add the Four Installments
Sum the interest amounts computed for each of the four quarters. That total is the penalty reported on the corporate return.
Reducing the Required Installment
Two alternative methods can lower the required installment for a given quarter when the standard 25-percent split does not match reality.
Annualized Income Installment Method
Corporations whose income arrives unevenly can annualize taxable income for specific periods and apply an applicable percentage to size each installment to the income actually earned so far:
- First installment: 25 percent of tax on income annualized from the first 3 months
- Second installment: 50 percent of tax on income annualized from the first 3 months, minus the first installment
- Third installment: 75 percent of tax on income annualized from the first 6 months, minus prior installments
- Fourth installment: 100 percent of tax on income annualized from the first 9 months, minus prior installments
The applicable percentages are 25, 50, 75, and 100 percent.3Office of the Law Revision Counsel. 26 USC 6655 – Failure by Corporation to Pay Estimated Income Tax Corporations can also elect alternative annualization periods (for example, 2, 4, 7, and 10 months) if those better fit the income pattern.7eCFR. 26 CFR 1.6655-2 – Annualized Income Installment Method
Any reduction in an early installment is recaptured in later installments. The method shifts timing; it does not erase a payment. Making the election requires completing Schedule A of Form 2220 and attaching it to the return.
Adjusted Seasonal Installment Method
A corporation with a pronounced seasonal pattern can use the adjusted seasonal installment method when at least 70 percent of taxable income over a base period falls within any six consecutive months.8eCFR. 26 CFR 1.6655-3 – Adjusted Seasonal Installment Method The method uses the income pattern from the three preceding tax years to set a base period percentage for each month, then scales installments to match. A corporation can use whichever method (standard, annualized, or seasonal) produces the lowest required installment for each quarter, provided the relevant schedule is completed.
CAMT Relief for 2025
For tax years beginning in 2025, the IRS is waiving the underpayment penalty on the portion of estimated tax attributable to Corporate Alternative Minimum Tax liability. Affected corporations still file Form 2220 but exclude CAMT liability when figuring the required annual payment. On the form, write “CAMT” next to Part I, line 1 and show the excluded amount in brackets.9Internal Revenue Service. Instructions for Form 2220 – Underpayment of Estimated Tax by Corporations Skipping those steps risks an automated penalty notice that then has to be resolved through a separate abatement request.
Asking for a Waiver
The IRS can waive the penalty on two grounds.
The first is a casualty, disaster, or other unusual circumstance that makes the penalty unfair. Corporations in a federally declared disaster area often receive automatic relief when FEMA issues a major disaster declaration with Individual Assistance, without a separate request.10Internal Revenue Service. IRS Offers Tax Relief After Major Disasters
The second is reasonable cause. The corporation must show it exercised ordinary business care and still fell short. Incorrect professional advice or a mid-year tax law change can qualify. Not knowing the rules does not.
To request a waiver, attach a written statement to Form 2220 explaining the specific facts: dates, amounts, what went wrong, and what the corporation did to comply. The IRS reviews the statement and decides whether to abate.
Filing the Form
Transfer the final penalty amount from Form 2220 to the penalty line of the corporate return (line 34 on Form 1120 for most C corporations). The amount increases tax owed or reduces the refund.
The form does not always have to be attached. The IRS can compute the standard penalty on its own and bill for it. Attachment is required only in three situations:1Internal Revenue Service. Instructions for Form 2220
- The corporation used the annualized income or adjusted seasonal method.
- A large corporation based its first installment on the prior year’s tax.
- A penalty waiver is being requested.
If none of those apply and the standard method was used, entering the penalty on the return without attaching Form 2220 is acceptable.
Short Tax Years
Corporations with a tax year shorter than 12 months cannot use the prior-year safe harbor. The instructions direct these filers to skip the prior-year tax line and base the required annual payment entirely on current short-year tax. Installment due dates also shift to match the abbreviated year, so a corporation that changed its fiscal year or was newly formed mid-year has to recalculate the schedule rather than default to the standard calendar dates.9Internal Revenue Service. Instructions for Form 2220 – Underpayment of Estimated Tax by Corporations
Overpaid Instead of Underpaid
A corporation that deposited more than it owes can request a quick refund using Form 4466 before filing the annual return. The overpayment must be at least $500 and at least 10 percent of expected tax liability. Form 4466 has to be filed after the tax year ends but no later than the original return due date, and before the return itself is filed. Extensions do not extend this deadline.11Internal Revenue Service. About Form 4466, Corporation Application for Quick Refund of Overpayment of Estimated Tax