Estimated Tax Penalty Calculator — Form 2210 Underpayment, Free

Will you owe an underpayment penalty on your estimated taxes?

Pay the smaller of 90% of this year's tax or 100% of last year's (110% for higher earners) across four installments, or the IRS charges interest on each shortfall. Enter your numbers to see the Form 2210 penalty by installment and what to pay to stop it.

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1. This year and last year

Tax year

Total tax you expect this year, incl. self-employment tax ($)

Income tax withheld and refundable credits ($)

Total tax on last year's return ($)

Last year's adjusted gross income ($)

Underpayment interest rate (%)

Married filing separately

Rate: the IRS republishes it each quarter (federal short-term rate plus 3 points). Check irs.gov/payments/quarterly-interest-rates and edit it if it differs.

2. Estimated payments you made

Leave a date blank to use that installment's due date (Apr 15, Jun 15, Sep 15, Jan 15). Payments are applied to the oldest unpaid installment first.

Payment 1 amount ($)

Payment 1 date

Payment 2 amount ($)

Payment 2 date

Payment 3 amount ($)

Payment 3 date

Payment 4 amount ($)

Payment 4 date

Enter this year's expected tax, then click Estimate penalty.

What this does not cover

Regular method only. The annualized income installment method (Form 2210 Schedule AI) can lower the penalty for uneven income and is not modelled.
One interest rate. The IRS rate can change each quarter; this uses the single rate you enter for the whole period.
Withholding is treated as paid evenly on the four due dates, the Form 2210 default.
Farmers, fishers, waivers (disaster, retirement, disability) and state penalties are not modelled.
Estimate, not a bill. The IRS computes the final figure on your return; use Form 2210 and its instructions to confirm.

Common questions

How is the underpayment penalty on estimated taxes calculated?

For each of the four installments (Apr 15, Jun 15, Sep 15, Jan 15) the IRS takes your required payment, subtracts what you paid by the due date, and charges the underpayment rate (federal short-term rate plus 3 points, 7% for recent quarters) on the shortfall for each day it stayed unpaid, until you paid it or the return due date. A payment is applied to the oldest unpaid installment first.

What is the safe harbor to avoid the penalty?

Pay 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), last year's tax must be multiplied by 110%. There is also no penalty if you owe under $1,000 after withholding and credits.

Does withholding count the same as estimated payments?

Yes, and it is treated as paid evenly on each due date unless you choose otherwise, even if it was withheld late in the year. That is why raising Q4 withholding can erase a penalty that estimated payments could not.

Can I reduce the penalty if my income came late in the year?

Yes. Form 2210 Schedule AI, the annualized income installment method, matches required payments to when you earned income. This calculator uses the regular method only, so it can overstate the penalty for seasonal or lumpy income.

Is this tax advice?

No. It applies published IRS rules to the numbers you enter and does not replace Form 2210 and its instructions or a qualified tax professional.