Quarterly Estimated Tax Penalty Calculator
Estimate your IRS Form 2210 underpayment penalty when quarterly estimated tax payments are missed or short. Uses the current 8% federal short-term rate (April 2026) and Q1-Q4 deadline windows.
Who Owes Estimated Tax Penalties?
If you expect to owe $1,000 or more in federal tax when you file your return and your withholding does not cover at least 90% of the current year or 100% of last year's liability (110% if prior AGI exceeded $150,000), the IRS requires quarterly estimated payments. Miss or underpay a quarter and Form 2210 assesses a penalty — essentially interest on the underpayment at the federal short-term rate plus 3%.
2026 Estimated Tax Deadlines
Q1: April 15 (income earned Jan 1 – Mar 31). Q2: June 15 (Apr 1 – May 31). Q3: September 15 (Jun 1 – Aug 31). Q4: January 15, 2027 (Sep 1 – Dec 31). Payments made late carry interest from the quarterly due date to either the payment date or April 15, 2027 — whichever comes first. Federal holidays shift deadlines to the next business day.
How the Penalty Rate Works
The IRS underpayment rate equals the federal short-term rate plus 3%. It resets quarterly. In Q2 2026 the rate is 8% annualized, which translates to about 0.022% per day. On a $10,000 underpayment outstanding for 90 days, that is roughly $197 in penalty. Penalty stops accruing when paid or on April 15 of the following year, whichever comes first.
How to Avoid Future Penalties
Use the safe harbor: pay 100% of last year's tax (110% if AGI > $150,000) in even quarterly installments and you owe nothing. Alternatively, use the annualized income method on Form 2210 Schedule AI if income is uneven (common for freelancers and seasonal workers). W-2 earners can also crank up withholding late in the year — withholding is treated as paid evenly across all four quarters, even if actually withheld in December.