United States · Form 2210
Estimated tax underpayment penalty calculator.
Enter your tax, withholding and the dates you paid. The page checks the IRS safe harbors first, then figures the penalty for each late or missed installment at the IRS quarterly rate.
You generally owe no underpayment penalty if you owe under $1,000 after withholding, or if you paid at least the smaller of 90% of this year's tax or 100% of last year's tax (110% if last year's AGI was over $150,000). Otherwise the penalty is the unpaid installment × days late ÷ 365 × the IRS rate, which is 7% for most of 2025 and 2026.
Your numbers
Result
How the penalty is figured
This page follows the regular method in Part III of Form 2210 (Section A, lines 10 to 18, and the Section B penalty worksheet). Each of the four installments is 25% of your required annual payment, which is the smaller of 90% of this year's tax and 100% of last year's tax (110% when last year's AGI was above $150,000, or $75,000 if married filing separately). Installments fall due April 15, June 15, September 15 and January 15 of the next year; a payment made on the next business day after a weekend due date counts as on time.
Your withholding is treated as paid one-fourth on each due date. Every payment, withholding included, is credited to the oldest unpaid installment first (IRC 6654(b)(2)), and a payment made before an installment is due is held and applied when it comes due. Whatever stays unpaid is charged from its due date until the day it was paid, or April 15 of the next year if it never was. For each rate period the charge is:
unpaid amount × days in the period ÷ 365 × IRS rate
The rate periods are April 16 to June 30, July 1 to September 30, October 1 to December 31, and January 1 to April 15, each at the IRS underpayment rate for that quarter. The rate is the federal short-term rate plus 3 percentage points, set quarterly (IRC 6621).
Worked example
Required annual payment $16,000 for 2025, so four installments of $4,000. You paid $2,000 on April 30, $3,000 on June 15, $4,000 on September 15 and $4,000 on January 15, 2026 (the IRS example in the Form 2210 instructions). The two payments after April 15 first clear the April installment ($2,000 on April 30 and $2,000 of the June payment), so $4,000 of April is unpaid for 15 days on $2,000 and 61 days on $2,000; the other $1,000 of the June payment is on time for June, leaving $3,000 unpaid on each of the June, September and January installments until the next payments arrive. At 7% the penalty is $5.75 + $23.40 (April, 15 and 61 days) + $52.93 (June, 92 days) + $70.19 (September, 122 days) + $51.78 (January, 90 days) = $204.05.
What this page does not do
It does not use the annualized income installment method (Schedule AI), which can cut or erase the penalty if your income arrived late in the year. It does not treat withholding as paid on the dates it was actually withheld (box D), request a waiver, or cover fiscal-year filers, farmers and fishers (66 2/3% test), estates or trusts. If you file a joint return this year but not last year, or the reverse, your prior-year figure has special rules on line 8 of the form. Unless you check box C or D, the IRS will usually figure the penalty and bill you, so you do not have to file Form 2210.
Official sources: IRS About Form 2210 (form and instructions, 2025 version used here), IRS Publication 505, chapter 4, IRS quarterly interest rates (page updated September 10, 2026) and 26 U.S.C. 6654.
IRS underpayment rates used
Non-corporate underpayment rate from the IRS quarterly interest rates page, checked October 2, 2026.
| Quarter | Rate | IRS source |
|---|---|---|
| Q2 2025 (Apr–Jun) | 7% | IRB 2025-13 |
| Q3 2025 (Jul–Sep) | 7% | IRB 2025-23 |
| Q4 2025 (Oct–Dec) | 7% | IRB 2025-37 |
| Q1 2026 (Jan–Mar) | 7% | IRB 2025-48 |
| Q2 2026 (Apr–Jun) | 6% | IRB 2026-8 |
| Q3 2026 (Jul–Sep) | 7% | IRB 2026-22 |
| Q4 2026 (Oct–Dec) | 7% | IRB 2026-36 |
| Q1 2027 (Jan–Mar) | not published | The calculator prefills 7% as a placeholder until the IRS posts the rate. |
Frequently asked questions
What is the safe harbor for estimated tax?
You avoid the penalty if your withholding and estimated payments for the year total at least the smaller of 90% of this year's tax or 100% of last year's tax. If last year's adjusted gross income was over $150,000 ($75,000 if married filing separately), the prior-year test is 110%. You also owe no penalty if you owe less than $1,000 after withholding.
Do I owe a penalty if I pay everything by April 15?
It can still apply. The penalty is figured installment by installment, so paying the full year's tax in April can leave the earlier installments late. The exception is withholding: if your withholding alone meets the required annual payment, there is no penalty however it was spread. Entering your dates here shows the effect.
What interest rate does the IRS use for the underpayment penalty?
The quarterly underpayment rate, which is the federal short-term rate plus 3 percentage points. It was 7% for every quarter of 2025 and for 2026 except April to June, when it was 6%. The rate for each period is shown in the table above and can be edited in the form.
Do I have to file Form 2210?
Usually not. If you owe a penalty and no special box applies, the IRS figures it and sends a bill. You file Form 2210 if you want a waiver, if you use the annualized income installment method, or if your penalty is lower when withholding is treated as paid on the dates it was actually withheld. A joint-return mismatch between the two years also requires page 1.
Can the penalty be waived?
The IRS waives all or part of it if it determines that you retired after reaching age 62 or became disabled in the tax year or the year before and the underpayment was due to reasonable cause, or that it was due to a casualty, disaster or other unusual circumstance and imposing the penalty would be inequitable. You request this with Form 2210 and a statement. This calculator does not apply any waiver.
Does withholding count as paid on time?
Yes. Unless you show otherwise, the IRS treats withholding as paid in four equal parts on the four due dates, even if most was withheld late in the year. That is why increasing your W-4 withholding late in the year can erase a penalty that estimated payments could not.
Cite this page: TNAADO Tools, "Estimated Tax Underpayment Penalty Calculator," tools.tnaado.ca/calculators/tax/estimated-tax-underpayment-penalty-calculator/, rates verified October 2, 2026 (IRS Form 2210 instructions, IRS quarterly interest rates).
Estimate only
This is an educational estimate of the Form 2210 regular method, not tax advice and not an IRS determination. The IRS computes the penalty it bills, and it may differ if you qualify for the annualized method, a waiver or other special rules. Nothing you enter leaves your browser.