Form2210Calc

IRS Underpayment Penalty Calculator

Missed or shorted a quarterly estimated tax payment? Run the Form 2210 math the IRS will run: your penalty per quarter, your safe-harbor verdict, and exactly what to pay to stop the daily meter. Free, no sign-up — everything stays in your browser.

Your numbers

Tax year

Form 1040 "total tax" (incl. self-employment tax), minus refundable credits. A solid estimate works.

From W-2s/1099s. The IRS treats it as paid evenly across all four quarters.

Sets your safe harbor. Enter 0 if you owed nothing. Leave blank if unknown — we'll use the 90% rule only.

Estimated payments you made for 2025

Dates are prefilled with the IRS due dates — change them to when you actually paid. Leave the amount blank for a quarter you skipped. Withholding goes in the field above, not here.

Q1

Q2

Q3

Q4

Your estimate

Enter your numbers to see the estimate

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IRS underpayment rate as of Q3 2026 · 7% (6% in Q2 2026) 2026 estimated-tax due dates →
This is an estimate, not tax advice. The IRS computes the official penalty amount — this tool applies the Form 2210 regular method with current published rates, but rounding, the annualized income method, withholding-date elections, and waivers can change the final figure. For decisions about your taxes, talk to a tax professional.

Questions people ask

How much is the penalty for not paying quarterly taxes?

It isn't a flat fee — it works like interest. The IRS charges its underpayment rate (7% for most of 2025–2026, 6% in Q2 2026) on each quarterly shortfall, counted day by day from the missed due date until you pay, or until the following April 15, whichever comes first. Example: a $4,000 installment paid 91 days late at 7% costs about $69.81. See the full math walkthrough.

What is the safe harbor rule (the "110% rule")?

Pay at least the smaller of 90% of this year's tax or 100% of last year's tax — 110% if your prior-year AGI was over $150,000 ($75,000 married filing separately) — through withholding and equal timely installments, and no penalty applies. Also: no penalty if you owe under $1,000 after withholding, or had zero tax liability last year. Full explainer + quick check.

Does the IRS have an official calculator for this?

No. The IRS will "figure it for you" after you file and send a bill — or you can fill out Form 2210 yourself. This tool runs the same regular-method math in your browser so you see the number before the bill arrives.

Can the penalty be waived or reduced?

Sometimes. Waivers exist for casualty/disaster and other unusual circumstances, and for people who retired after 62 or became disabled with reasonable cause (Form 2210 Part II). If your income arrived unevenly — say, mostly in Q4 — the annualized income method (Schedule AI) can shrink the penalty. This calculator uses the standard method, so Schedule AI can only make your real number lower.

Is this number exactly what I'll pay?

It's a close estimate using the official method and current IRS quarterly rates. The IRS computes the official amount, and rounding or elections can move it slightly. Estimate, not advice.