Free calculator · tax year 2026
Underpayment penalty calculator for 2026
Missed a quarterly payment, or paid less than you should have? Enter your tax and what you paid, and see the estimated tax penalty the IRS will charge for each quarter. It works the way Form 2210 does, at the IRS interest rate for each day, and nothing you type leaves your browser.
Underpayment penalty calculator · 2026
Form 2210’s regular method: each quarter’s shortfall, charged the IRS interest rate for each day it stayed unpaid.
Total tax after credits, including self-employment tax.
The total tax line of your 2025 Form 1040.
From a W-2 job, for example. It counts as paid evenly on the four due dates.
The penalty stops on April 15, 2027, even if you pay after that.
| Due | Needed | Paid | Penalty |
|---|---|---|---|
| Apr 15 | $2,500 | $2,500 | $0.00 |
| Jun 15 | $2,500 | $0 | $43.08 |
| Sep 15 | $2,500 | $5,000 | $0.00 |
| Jan 15 | $2,500 | $2,500 | $0.00 |
| Estimated penalty | $43.08 | ||
You needed $10,000 for the year (100% of 2025 tax, the smaller safe harbor), so $2,500 by each due date. A payment covers the oldest shortfall first.
An estimate, not a bill. The IRS works out the actual amount and usually sends it to you.
How the penalty is worked out
For 2026 you needed to pay, through withholding and on-time estimated payments, the smaller of 90% of your 2026 tax or 100% of your 2025 tax (110% if your 2025 AGI was over $150,000). That’s the safe harbor. A quarter of it was due on each of the four due dates.
Whatever was short on a due date is charged interest at the IRS underpayment rate, every day until it’s paid or until April 15, 2027, whichever comes first. The rate was 7% for January to March 2026, 6% for April to June, and 7% for July to December. A later payment pays off the oldest shortfall first, even if you meant it for the current quarter.
When there’s no penalty at all
- Your 2026 tax, minus withholding, is less than $1,000.
- You had no tax for 2025, on a return covering all 12 months, and were a US citizen or resident all year.
- You file your 2026 return by February 1, 2027 and pay everything, which covers the January payment.
Do you need to file Form 2210?
Usually not. The IRS works the penalty out and sends a bill, and tax software adds it to your return. You file Form 2210 yourself only to ask for a waiver, to use the annualized income method if most of your income came late in the year, or to count withholding on the dates it was taken out. Our Form 2210 guide explains each of those.
State penalties are separate
Most states with an income tax charge their own penalty on top, with their own rules. California wants 30%, 40%, 0% and 30% of the year’s tax on the four dates, New York charges a higher rate, and New Jersey only needs 80% of this year’s tax. See the guides for California, New York and New Jersey.
Not paying it again next year
The cheapest fix is to pay a quarter of your safe-harbor amount on each due date. The free 1099 tax calculator works that out from your expected income, and our guide to paying online shows the free ways to send it.
Know before each due date, not after.
The Paid & Filed Workbook ($29) works out each quarterly payment from your real income and keeps a log of what you’ve paid, so you can see before the due date whether you’re covered.