IRS Form 2220: Corporate Estimated Tax Underpayment Penalty and Waivers

IRS Form 2220 is the worksheet a corporation uses to figure the penalty it owes when quarterly estimated tax payments fell short. The penalty is not a flat fee. It is an interest charge calculated separately for each of the four installments, running from the due date until the shortfall was paid or until the return due date, whichever comes first. Get the inputs right and the form does the arithmetic; get them wrong and the IRS will recalculate and bill you.

Who Has to File and When Payments Are Due

Any corporation that expects to owe $500 or more in federal income tax for the year must make quarterly estimated payments. S corporations, tax-exempt organizations with unrelated business income tax, and private foundations are all covered by the same rule and use Form 2220 to figure any penalty.¹

Installments are due on the 15th day of the 4th, 6th, 9th, and 12th months of the tax year. For a calendar-year corporation that means April 15, June 15, September 15, and December 15. A weekend or federal holiday pushes the deadline to the next business day.²

Figuring the Required Annual Payment

The required annual payment is the total a corporation needs to deposit across the year to avoid a penalty. It equals 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-month tax year and the corporation filed a return showing some tax liability.³

Each installment is 25 percent of that annual figure. If the required annual payment is $200,000, each quarter needs $50,000. Any shortfall on a due date becomes an underpayment that drives the penalty calculation.

The 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. These corporations can only use the prior-year amount for the first installment. The other three must be based on 100 percent of the current year’s expected tax.³

If a large corporation uses the prior-year figure for Q1 and that amount is less than 25 percent of the current year’s tax, the gap has to be made up with the Q2 installment.⁴

How the Penalty Is Calculated

Form 2220 handles each quarterly underpayment on its own. Three inputs drive the result: the amount underpaid, how long it stayed unpaid, and the IRS interest rate for the days in between.

The Underpayment Amount

For each installment date, compare what the corporation actually deposited to what it was required to pay. The shortfall is the underpayment for that quarter. A quarter paid on time and in full generates no penalty regardless of what later quarters look like.

The Penalty Period

The clock starts on the installment due date and stops on the earlier of two dates: the day the shortfall was paid, or the 15th day of the 4th month after the tax year closes. For a calendar-year filer, that outer date is April 15 of the following year.³

A late payment that lands before the next installment date shortens the penalty window for the earlier quarter. On big underpayments, even a few days matter.

The Interest Rate

The IRS resets the underpayment rate quarterly. The standard corporate rate is the federal short-term rate plus 3 percentage points and compounds daily.⁵ Large corporate underpayments carry a higher rate: the federal short-term rate plus 5 percentage points, which applies to any portion still outstanding after the IRS sends a notice or the return is filed.⁶

For the first half of 2026, the standard corporate underpayment rate is 6 percent. The large corporate underpayment rate was 9 percent in Q1 and 8 percent in Q2.⁷ Because the rate changes every three months, a penalty period that crosses quarters uses each quarter’s rate for the days falling inside it.

Adding It Up

Calculate the interest charge for each of the four installments and add them. That total is the penalty the corporation reports on its income tax return. Form 2220 lays out this arithmetic line by line, with columns for the due dates, payment dates, underpayment amounts, and daily interest.

Lower Installments for Uneven Income

A corporation that earns income unevenly across the year can elect the annualized income installment method on Schedule A of Form 2220. Instead of requiring 25 percent of annual tax every quarter, this method ties each installment to income actually earned by that point in the year. It uses applicable percentages of 25, 50, 75, and 100 percent applied to the tax on annualized income for 3, 3, 6, and 9 months of the year. Corporations whose income pattern fits better with 2, 4, 7, and 10 months can elect those alternative periods instead.⁸

Any reduction in an early installment has to be recaptured in later ones. The method shifts the timing to match when income arrives; it does not reduce the total required payment.³ The election is not automatic. Skip Schedule A and the IRS treats the standard installments as required.

Businesses with a clear seasonal pattern have a second option: the adjusted seasonal installment method. It is available when at least 70 percent of the corporation’s taxable income over a base period falls within any six consecutive months.⁹ A corporation can use whichever of the three methods produces the lowest required installment for each quarter.

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 from the required annual payment calculation. Write “CAMT” next to Part I, line 1 and show the excluded amount in brackets.¹⁰ Skipping that notation can trigger an automated penalty notice that then takes an abatement request to clear.

When to Attach the Form

Corporations do not always have to attach Form 2220 to their return. The IRS can run the standard calculation itself and bill any shortfall. Attachment is required in three situations:¹

The corporation used the annualized income or adjusted seasonal method. The IRS cannot see an alternative election without the schedule.
A large corporation based its first installment on the prior year’s tax and needs to show that calculation.
The corporation is requesting a penalty waiver and needs to attach the explanatory statement.

Otherwise, the penalty amount can be entered on the return without attaching the form. The final figure goes on the penalty line of the corporation’s income tax return and either increases the balance due or reduces the refund.

Short Tax Years

A tax year shorter than 12 months takes the prior-year safe harbor off the table. Filers skip the prior-year tax line on Form 2220 and base the required annual payment entirely on the current year’s tax. Installment due dates shift to track the abbreviated year, so newly formed corporations and those that changed fiscal years recalculate the schedule rather than using the standard calendar dates.¹⁰

Requesting a Waiver

Two grounds support a waiver request. The first is a casualty, disaster, or other unusual circumstance that would make imposing the penalty unfair. Corporations in a federally declared disaster area with Individual Assistance usually get automatic relief when the IRS extends deadlines for the area.¹¹

The second is reasonable cause: the corporation exercised ordinary business care in determining its obligations and still fell short. Incorrect professional advice or a mid-year law change can qualify. Not knowing the rules does not. Attach a detailed written statement to Form 2220 with dates, amounts, what happened, and the steps the corporation took to comply, along with supporting documentation.

Overpaid Instead?

Form 2220 only addresses underpayments. A corporation that deposited more than it owes can use Form 4466 to request a quick refund before filing the annual return. The overpayment must be at least $500 and at least 10 percent of expected tax liability. Form 4466 is due after the tax year ends but no later than the original return due date, must be filed before the return itself, and extensions do not extend the deadline.¹²

1
Internal Revenue Service. Instructions for Form 2220
2
Internal Revenue Service. Underpayment of Estimated Tax by Corporations Penalty
3
Office of the Law Revision Counsel. 26 USC 6655
4
Legal Information Institute. 26 USC 6655(g)(2)
5
Internal Revenue Service. Topic No. 653
6
Office of the Law Revision Counsel. 26 USC 6621
7
Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026
8
eCFR. 26 CFR 1.6655-2
9
eCFR. 26 CFR 1.6655-3
10
Internal Revenue Service. Instructions for Form 2220
11
Internal Revenue Service. IRS Offers Tax Relief After Major Disasters
12
Internal Revenue Service. About Form 4466