Underpayment Penalty Calculator
Estimate the IRS penalty the way Form 2210 figures it, quarter by quarter, for this year or the return you just filed, and see whether it should be lower.
Use your best estimate of this year's figures. Payments dated in the future are treated as made on that date.
Form 1040, line 24. This is after credits and includes self-employment tax.
Form 1040, line 25d. Enter 0 if nothing was withheld.
Earned income credit, additional child tax credit, and the other credits on Form 1040 lines 27 through 31. Most filers leave this at 0.
Last year's Form 1040, line 24. This sets your safe harbor amount.
Each payment with the date it was sent. Leave a row blank if you skipped that quarter. A 2025 refund you applied to 2026 counts as a payment dated Apr 15, 2026.
This is the figure the IRS bills when you file without Form 2210. It assumes you owed $4,500 at each deadline, a quarter of your $18,000 required annual payment.
| Quarter | Due | Underpaid | Days late | Penalty |
|---|---|---|---|---|
| Q1 | Apr 15, 2026 | $4,500 | 365 | $305.63 |
| Q2 | Jun 15, 2026 | $4,500 | 304 | $260.51 |
| Q3 | Sep 15, 2026 | $4,500 | 212 | $182.96 |
| Q4 | Jan 15, 2027 | $4,500 | 90 | $77.67 |
Interest at 6% to 7% a year on each shortfall, from its due date to the day it was paid or to Apr 15, 2027, whichever came first. Withholding is credited in four equal parts on the due dates. The IRS has not announced the rate for Jan 1, 2027 onward yet. This assumes it stays at 7%.
Did your income arrive unevenly?
The annualized income method sizes each installment to what you had actually earned by that deadline. If a big share of your income came late in the year, it can lower this penalty or remove it. The full calculator runs both methods and produces the Form 2210 and Schedule AI to file.
How the penalty is figured
The penalty is interest, not a fine. Form 2210 starts by finding your required annual payment, the smaller of 90% of this year's tax and 100% of last year's tax (110% if last year's AGI was over $150,000). Under the regular method a quarter of that amount was due at each of the four deadlines. For every deadline you fell short, interest runs on the shortfall from the due date until the money came in.
Payments are applied to the oldest shortfall first, whatever quarter you meant them for, and withholding is spread evenly across the four dates no matter when it happened. Both rules come from the Form 2210 instructions, and both are built into this calculator.
When the number should be lower
The regular method assumes your income arrived in four even pieces. If it did not, the IRS offers the annualized income method instead. It looks at the income you had actually received by March 31, May 31, and August 31, and requires only the tax on that. A freelancer whose big client paid in November, or an investor who sold in December, owed far less in the spring than a quarter of the year's total, and the penalty on those early quarters drops accordingly.
The IRS does not apply this method for you. You claim it by filing Form 2210 with Schedule AI and checking box C, either with your return or in response to a penalty notice. Our guide, how to lower an IRS underpayment penalty, covers that and the other grounds for relief. The annualized income method guide explains the calculation itself.
What this calculator does not cover
It figures the federal penalty for 2026 returns, filed in 2027, using the regular method. It does not apply the actual withholding dates of box D, the waivers of Part II, or the farmer and fisherman rules of Form 2210-F, and it does not compute state penalties. If a payment arrived after Apr 15, 2027, the IRS charges interest past that date on top of the amount shown here.
Frequently asked questions
This is just one piece
Get your complete quarterly estimate. Every income type, federal and state, penalties, and the method that pays the least, combined in one place.