Estimated Tax Penalty: How It Works and How to Avoid It

Quick answer: The estimated tax penalty is an interest-style charge the IRS adds when you do not pay enough tax during the year through withholding or quarterly payments. You generally avoid it if you owe less than $1,000, or if you paid at least 90% of this year's tax or 100% of last year's (110% if last year's AGI was over $150,000).

If you freelance, run a side business or own rental property, nobody withholds tax from your income for you. The US tax system still expects that tax to arrive during the year, not in one lump in April. When it does not, the IRS adds an underpayment penalty, reported on Form 2210 for individuals. The good news is that it is one of the most predictable and avoidable charges the IRS makes. This guide explains how the estimated tax penalty is calculated, the safe harbors that protect you, the current rate and what to do if you already owe it.

Important: This is general information, not tax advice. Rules differ for farmers, fishers, household employers and estates, and your state may charge its own penalty. Check with a qualified tax adviser about your situation.

What the estimated tax penalty is

Federal income tax is a pay-as-you-go tax. Employees pay through payroll withholding. Self-employed people, investors and landlords pay through quarterly estimated tax payments using Form 1040-ES. If those payments (plus any withholding) fall short of what the law requires for a given installment, the IRS charges a penalty on the shortfall for each day it stays unpaid.

Three things about it surprise people:

• It is calculated quarter by quarter. Paying everything in January does not wipe out penalties for April, June and September.
• You can owe it even with a refund. The IRS is explicit about this: a late estimated payment can be penalized even if you are due money back when you file.
• It is not the same as the late payment penalty. The failure-to-pay penalty applies to tax unpaid after the April filing deadline. The underpayment penalty covers the months before that.

If you are new to quarterly payments, start with our guide to quarterly estimated taxes for freelancers, which covers how to work out each payment.

Who has to pay estimated tax

You generally need to make estimated payments if you expect to owe $1,000 or more when you file, after subtracting withholding and refundable credits. That catches most freelancers and sole proprietors who make a profit, because self-employment tax alone is 15.3% of most of your net earnings, on top of income tax.

Common triggers include:

• Profit from a business reported on Schedule C.
• Rental income, interest, dividends and capital gains with no withholding.
• A side gig on top of a salaried job where your employer's withholding does not cover the extra income.
• A large one-off gain, such as selling shares or a property, during the year.

The safe harbors that protect you

The IRS will not charge an underpayment penalty if you meet any one of these tests:

Test	What you must pay on time	Best for
Under $1,000	Balance due after withholding and refundable credits is less than $1,000	Small side income
90% current year	At least 90% of this year's total tax	Income that fell this year
100% prior year	At least 100% of the tax shown on last year's return (a full 12-month return)	Income that is rising or unpredictable
110% prior year	At least 110% of last year's tax if last year's AGI was over $150,000 ($75,000 married filing separately)	Higher earners
No liability last year	You had no tax liability for a full 12-month prior year and were a US citizen or resident	First year in business after a year with no tax

The prior-year safe harbor is the one most freelancers rely on, because you know the number in advance. Divide last year's total tax (100% or 110%) by four and pay that amount on each due date. Even if you earn far more this year, you will owe the difference in April but no estimated tax penalty.

Worked example: choosing a safe harbor

Maria is a self-employed designer. Her 2025 return showed total tax of $18,000 and AGI of $120,000. Using the 100% rule, she pays $4,500 on each 2026 due date. In 2026 her business grows and her actual tax is $26,000. She owes $8,000 when she files, but no underpayment penalty, because she paid 100% of last year's tax on time.

Her colleague James had 2025 AGI of $180,000 and total tax of $40,000. Because his AGI was over $150,000, he needs 110%: $44,000, or $11,000 a quarter. If he only paid $10,000 a quarter, he would miss the safe harbor unless his 2026 tax turned out to be $44,444 or less (so that $40,000 covered 90% of it).

2026 due dates

For the 2026 tax year, the four installments are due:

1. April 15, 2026 (income from January 1 to March 31)
2. June 15, 2026 (April 1 to May 31)
3. September 15, 2026 (June 1 to August 31)
4. January 15, 2027 (September 1 to December 31)

The periods are not equal quarters, which is why the second payment comes only two months after the first. If you file your 2026 return and pay all the tax due by February 1, 2027, the Form 1040-ES instructions say you do not need to make the January payment.

How the penalty is calculated and the current rate

The underpayment penalty is figured separately for each installment. For each one, the IRS takes the amount you were short and multiplies it by the underpayment interest rate for the number of days it was late, until it was paid or until the April filing deadline, whichever comes first.

The rate is the federal short-term rate plus three percentage points, reset each quarter. According to the IRS quarterly interest rates page, the individual underpayment rate for 2026 is:

Quarter	Underpayment rate
January to March 2026	7%
April to June 2026	6%
July to September 2026	7%
October to December 2026	7%

The IRS announced in August 2026 that the 7% rate would hold for the fourth quarter. The rate for January to March 2027 had not been published at the time of writing, so check the IRS page if you are estimating a penalty that runs into next year.

Worked example: what a missed payment costs

Say your required installment for September 15 was $3,000 and you paid nothing until December 14, 90 days later. At 7%, the approximate penalty is $3,000 x 7% x 90 / 365 = about $52. Small, but it adds up across four quarters and several years, and it is entirely avoidable. Missing all four installments of $5,000 on a $20,000 liability could easily cost a few hundred dollars.

When and how to use Form 2210

Form 2210, Underpayment of Estimated Tax by Individuals, Estates, and Trusts, is where the penalty is calculated. In many cases you do not need to file it: if you owe a penalty, you can leave the line blank and the IRS will compute it and send a bill. You would file Form 2210 when you want to:

• Request a waiver of all or part of the penalty.
• Use the annualized income installment method (Schedule AI) because your income arrived unevenly.
• Treat withholding as paid on the actual dates it was withheld, rather than spread evenly across the year.
• Base the safe harbor on last year's tax when the IRS would not otherwise know you qualify, such as when last year's return was filed jointly and this year's separately.

Most tax software completes Form 2210 for you and tells you whether the annualized method would help.

Ways to avoid the penalty

1. Use the prior-year safe harbor. Pay 25% (or 27.5%) of last year's tax on each due date and stop worrying about forecasting.
2. Raise your withholding if you also have a job. Withholding is treated as paid evenly throughout the year, so increasing it on a new Form W-4 in October can repair an underpayment from April.
3. Set aside tax on every invoice. Many freelancers move 25% to 30% of each payment into a separate tax account the day it arrives. Our guide to a business bank account for freelancers explains how to set this up.
4. Annualize if income is seasonal. Landing a large contract in November should not mean a penalty for April.
5. Keep clean income records. You cannot estimate tax from income you have not tracked. Numbered invoices from our free invoice generator and a simple profit and loss statement each quarter make the calculation quick.

Special situations

Your first year in business

If you were employed last year and your withholding covered your full tax bill, you may already be protected in your first freelance year. The prior-year safe harbor only asks you to pay 100% (or 110%) of last year's total tax, and withholding from a job you held earlier in the year counts. If last year's total tax was zero and you were a US citizen or resident for the whole year, you owe no underpayment penalty this year at all, even if you make no estimated payments. You will still owe the tax itself in April, so set money aside.

Farmers and fishers

If at least two-thirds of your gross income comes from farming or fishing, special rules apply. You generally make one payment by January 15 of the following year, or file and pay in full by March 1, and the required amount is based on 66 2/3% of the current year's tax rather than 90%. These taxpayers use Form 2210-F instead of Form 2210.

Married couples

Joint filers can make joint estimated payments, and the safe harbor applies to the joint tax. If you filed jointly last year but file separately this year, or the other way round, the prior-year figure has to be split, and the Form 2210 instructions explain how. The $150,000 AGI threshold for the 110% rule drops to $75,000 for married filing separately.

Household employers

If you pay a nanny or other household employee and report their employment taxes on Schedule H, those taxes count toward your total tax. You can cover them through estimated payments or extra withholding from your own wages to avoid an underpayment.

What to do if you already owe the penalty

If it is late in the year and you have paid nothing, act now rather than waiting for April. The penalty runs daily, so every payment you make stops the clock on the shortfall it covers, even though it cannot erase penalties already built up on missed installments. A practical approach:

1. Work out your likely total tax using your income so far and a realistic estimate for the rest of the year.
2. Compare it with the safe harbors to find the minimum you still need to pay.
3. Make a payment straight away through IRS Direct Pay, EFTPS or your IRS online account, and choose estimated tax for the correct year.
4. If you have a W-2 job, increase withholding for the rest of the year, since withholding is treated as spread evenly over the whole year.
5. When you file, let your software test the annualized income method in case it lowers the bill.

Then pay the penalty when you file or when the IRS bills you. It is usually far smaller than the late payment and late filing penalties that apply after April, so filing on time is still the priority.

Waivers and penalty relief

The estimated tax penalty has narrower relief than other IRS penalties. First-time abatement, and the new Automatic Exemption from Penalty the IRS introduced in 2026, apply to failure-to-file, failure-to-pay and failure-to-deposit penalties, not to the underpayment penalty. The only waivers are:

• You did not make a payment because of a casualty, disaster or other unusual circumstance, and it would be inequitable to impose the penalty.
• You retired after reaching age 62, or became disabled, in the tax year or the year before, and the underpayment was due to reasonable cause and not willful neglect.

You request a waiver by filing Form 2210 with a statement explaining why. The IRS also announces automatic waivers in some years, for example for taxpayers in federally declared disaster areas, so it is worth checking the news on IRS.gov. For other penalties, see our guide to IRS penalty abatement.

Conclusion

The estimated tax penalty is small compared with the tax itself, but it is also the easiest IRS charge to avoid. Pick a safe harbor, put the four due dates in your calendar, and set aside tax every time a client pays. Start with organized income records: create numbered, professional invoices with our US invoice generator, and the quarterly maths becomes a five-minute job. For more guides, browse our tax compliance articles.