Why this penalty exists
The U.S. tax system is “pay as you go”. Employees pay through withholding on every paycheck; 1099 workers are expected to pay through quarterly estimated payments. If you pay too little, too late, the IRS adds a penalty for underpayment of estimated tax, even if you pay the full tax when you file.
When you owe it (and when you don’t)
You generally owe the penalty if you did not pay enough through withholding and on-time estimated payments. You are protected if any of these apply:
- You owe less than $1,000 after subtracting withholding and refundable credits.
- You paid at least 90% of this year’s tax during the year.
- You paid at least 100% of last year’s tax during the year (110% if last year’s adjusted gross income was over $150,000, or $75,000 if married filing separately).
- You had no tax liability last year, were a U.S. citizen or resident for the whole year, and that return covered 12 months.
The prior-year rule is the most useful one for people whose income is growing: pay one quarter of last year’s total tax on each due date and you are safe, even if you end up owing more in April.
How the penalty is calculated
- 1st paymentIncome from Jan 1 – Mar 31 · 3 monthsDue
- 2nd paymentIncome from Apr 1 – May 31 · 2 monthsDue
- 3rd paymentIncome from Jun 1 – Aug 31 · 3 monthsDue
- 4th paymentIncome from Sep 1 – Dec 31 · 4 monthsDue
You can skip the 4th payment if you file your 2026 return and pay everything by February 1, 2027.
The penalty works like interest on each late payment:
- The IRS splits your required annual payment into four installments, one per due date (April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027 for 2026).
- For each installment, it looks at how much you were short and for how many days, until you paid or until the filing deadline.
- It applies the IRS underpayment rate, which is set every quarter. For the quarter starting October 1, 2026, the rate is 7% a year.
Example. If a $2,000 quarterly payment arrives 90 days late at a 7% annual rate, the penalty is about $34.52 ($2,000 × 7% × 90 ÷ 365).
So the penalty is usually modest, but it adds up across quarters, and it is money you do not need to spend.
Exceptions, waivers and uneven income
- Annualized income method. If most of your income came late in the year, you can show on Form 2210, Schedule AI, that you owed less in the earlier quarters. This can reduce or remove the penalty.
- Waivers. The IRS can waive the penalty if the underpayment was due to a casualty, disaster or other unusual circumstance, or if you retired after age 62 or became disabled during the year or the year before and had a reasonable cause.
- January payment. You can skip the January 15, 2027 installment if you file your 2026 return and pay everything by February 1, 2027.
Already behind? What to do now
- Pay as soon as you can. Each day earlier means a smaller penalty. IRS Direct Pay is free.
- Catch up in your next payment. Add the missed amount to the next installment. Our quarterly estimated tax calculator does this for you when you enter what you already paid.
- Use withholding if you have a W-2 job. Tax withheld from wages is treated as paid evenly on all four due dates, even if it is withheld late in the year. Raising your withholding with a new Form W-4 can cover earlier quarters.
- Plan next year with the safe harbor. Divide this year’s total tax by four and pay that on each date next year.
To understand what you owe overall, start with our beginner’s guide to 1099 taxes.