If you expect to owe $1,000 or more when you file and nobody is withholding for you, the IRS wants the money in four pieces during the year, not one piece in April. That covers most self-employed people, landlords, retirees with investment income, and anyone with a side business.
The 2027 dates
- April 15, 2027, for January through March
- June 15, 2027, for April and May
- September 15, 2027, for June through August
- January 18, 2028, for September through December (the 15th is a Saturday and the 17th is a federal holiday)
The quarters are not equal. Q2 is two months. Q4 is four. The IRS calls them quarters anyway.
How much
Enough to reach one of two safe harbors: 90 percent of the tax you will owe this year, or 100 percent of last year's tax (110 percent if your adjusted gross income was over $150,000). Most people pick last year's number because it is known. Divide by four, pay on the dates, and the underpayment penalty cannot touch you even if this year turns out bigger.
What it costs to skip
The underpayment penalty is interest by another name: the IRS underpayment rate (7 percent for the fourth quarter of 2026) applied to each missed installment from its due date until paid or until April 15. It is not a fine, it is a rent charge, and it is not abatable under first-time abatement.
Common mistake
Waiting to see how the year goes and paying it all in Q4. The penalty is computed per quarter, so a big January payment does not cure a missed April one.
Sources
- IRS, Estimated taxes
- IRS, About Form 1040-ES
- IRS, Quarterly interest rates