What is the underpayment penalty?

It is interest charged when you paid too little during the year. The rate changes quarterly and the IRS sets it. Hitting a safe-harbor amount protects you even if you still owe at filing.

Can I raise my W-2 withholding instead of paying quarterly?

Yes. Withholding counts the same as estimated payments toward safe harbor. Many people with a job and a side business adjust their W-4 instead.

I missed a quarterly payment. What now?

Pay it as soon as you can. The penalty is figured period by period, so catching up stops the meter from running. File Form 2210 with your return to let the IRS compute the penalty, or let your tax software handle it.

Does the underpayment penalty apply if I get a refund?

It can. The penalty looks at whether you paid enough during the year, not at your final balance. Paying in April what you owed in June can still trigger it, even if your return shows a refund.

Federal rules for readers across the U.S.

Estimated Quarterly Taxes, Plainly Explained

By Christian Brinkley. Reviewed October 8, 2026.

Educational information only, not personalized tax, legal, or investment advice. Christian is a licensed insurance agent (NC Life & Health), not a CPA or registered investment adviser. Discuss your own situation with a qualified professional.

Who has to pay

The IRS expects estimated payments when you will owe at least $1,000 after withholding and credits. Self-employed workers pay because no employer withholds for them. People with rental or investment income may owe them too. W-2 employees with side income can fall in as well.

The four due dates

Payments are due April 15, June 15, and September 15 of the current year. The fourth payment is due January 15 of the next year. A date that lands on a weekend or holiday moves to the next business day. Each payment covers the income earned in that slice of the year.

Safe harbor rules

You dodge the underpayment penalty by paying 90% of this year's tax. You can also pay 100% of last year's tax as a safe harbor. If last year's AGI was above $150,000, the safe harbor rises to 110%. State rules differ, so check your state separately.

The 2026 dates on the calendar

For 2026 income, payments land on April 15, June 15, and September 15, 2026, with the final one due January 15, 2027. If a date falls on a weekend or holiday, it slides to the next business day. The year gets sliced into uneven chunks: the June payment covers only two months of income while the September one covers three. That's why the IRS calls them payment periods, not quarters.

How to actually send the money

The fastest route is IRS Direct Pay or the IRS2Go app, straight from your bank account, and you get a confirmation number on the spot. EFTPS works too once you're enrolled. Paper filers mail Form 1040-ES with a voucher and a check. You can also pay weekly or monthly as long as each period's total is in by its due date. Whichever way you pay, save the confirmation with your tax records.

Uneven income gets its own method

If most of your money arrives late in the year, equal quarterly payments can overpay early and still leave you penalized. The IRS lets you annualize: match each payment to the income actually earned in that period, using Schedule AI of Form 2210. Freelancers with lumpy income, landlords with a big fourth-quarter sale, and anyone with a mid-year windfall should know this exists. It takes more math, but it can cut the penalty down to size.

Safe harbor methods and penalty protection
Topic	How they compare
Pay 90% of current-year tax	Protected if you hit it
Pay 100% of prior-year tax	Protected; 110% when AGI topped $150,000
Pay less than safe harbor	Underpayment penalty can apply

Your records checklist

Estimate this year's income, deductions, and total tax.
Divide what you will owe into four payments.
Pay by April 15, June 15, September 15, and January 15.
Keep proof of each payment with your tax records.

Common questions

What is the underpayment penalty?: It is interest charged when you paid too little during the year. The rate changes quarterly and the IRS sets it. Hitting a safe-harbor amount protects you even if you still owe at filing.
Can I raise my W-2 withholding instead of paying quarterly?: Yes. Withholding counts the same as estimated payments toward safe harbor. Many people with a job and a side business adjust their W-4 instead.
I missed a quarterly payment. What now?: Pay it as soon as you can. The penalty is figured period by period, so catching up stops the meter from running. File Form 2210 with your return to let the IRS compute the penalty, or let your tax software handle it.
Does the underpayment penalty apply if I get a refund?: It can. The penalty looks at whether you paid enough during the year, not at your final balance. Paying in April what you owed in June can still trigger it, even if your return shows a refund.

Sources and current instructions

Check the tax year and any later updates before acting. These are the primary sources used for this guide.