Question 1

What is the IRS underpayment penalty?

Accepted Answer

The IRS charges an underpayment penalty (Form 2210) when you don't pay enough estimated tax throughout the year. The penalty is essentially interest on the underpaid amount, calculated at the federal short-term rate plus 3 percentage points (8% for 2026).

Question 2

When are quarterly estimated tax payments due?

Accepted Answer

Quarterly payments are due April 15, June 15, September 15, and January 15 of the following year. If a due date falls on a weekend or holiday, the deadline moves to the next business day.

Question 3

How can I avoid the underpayment penalty?

Accepted Answer

You can avoid the penalty by paying at least 90% of your current year tax liability or 100% of your prior year tax liability (110% if your AGI exceeded $150,000) through withholding and estimated payments.

Question 4

Is there a safe harbor for estimated taxes?

Accepted Answer

Yes, the IRS 'safe harbor' rule means you won't owe a penalty if you paid at least 100% of your prior year's tax liability (110% if AGI > $150,000) through withholding and estimated payments, regardless of your current year tax.

Question 5

Can I waive the estimated tax penalty?

Accepted Answer

The IRS may waive the penalty if you underpaid due to a casualty, disaster, or other unusual circumstance, or if you retired after age 62 or became disabled during the tax year. You can request a waiver using Form 2210.

Question 6

How is the penalty calculated for each quarter?

Accepted Answer

The penalty is calculated separately for each quarter based on the underpaid amount and the number of days from the payment due date to the earlier of the payment date or April 15 of the following year. The daily rate is the annual penalty rate divided by 365.

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