The IRS charges an underpayment penalty when you do not pay enough tax throughout the year to cover what you will owe at filing time

The underpayment penalty (also called the estimated tax penalty) applies when the total of your withholding plus estimated tax payments falls short of what you actually owe. The IRS does not charge this penalty because you filed late or owed money — it charges it because you did not send in enough during the tax year itself. The penalty is calculated on the shortfall amount, using an interest rate that changes quarterly.

You trigger the penalty by underpaying in two ways: either your employer withheld too little from your paychecks, or you did not make quarterly estimated tax payments when you should have. The IRS measures your payment against a threshold — usually 90 percent of your current year tax or 100 percent of your prior year tax (110 percent if your prior year adjusted gross income was over $150,000). If you fall short of that threshold, you owe the penalty on the gap.

The penalty is separate from the tax itself. You pay both the unpaid tax and the penalty when you file. The penalty does not reduce your tax bill — it is an additional cost for underpaying during the year.

Key Takeaways

  • The underpayment penalty applies when your total tax payments during the year (withholding plus estimated payments) fall below 90 percent of your current year tax or 100 percent of your prior year tax.
  • The penalty is calculated quarterly on the shortfall amount using an IRS interest rate that changes every three months.
  • You can avoid the penalty by adjusting your W-4 withholding mid-year, making catch-up estimated payments, or meeting a safe harbor threshold before year-end.
  • The penalty applies to self-employed people, investors, and anyone with income not subject to withholding, as well as employees whose employers withheld too little.
  • Form 2210 is used to calculate the penalty and report it on your tax return, though the IRS often calculates it for you if you do not claim an exception.

Who the IRS charges the underpayment penalty to

The penalty applies to anyone whose total tax payments fall short during the year. This includes self-employed people who owe quarterly estimated taxes, investors with capital gains or dividend income, retirees taking distributions from retirement accounts, and employees whose employers withheld too little.

You are most likely to face this penalty if you have income that is not subject to withholding — such as business income, rental income, or investment gains — and you do not make quarterly estimated payments. But you can also trigger it if you are an employee and your W-4 withholding is set too low. The penalty does not care where the shortfall came from, only that it exists.

The IRS does not charge the penalty if your total tax liability for the year is under $1,000. This is a hard floor: if you owe $999 or less, no penalty applies regardless of how much you underpaid.

The two thresholds that determine whether you owe a penalty

The IRS uses a safe harbor system: if you meet either of two thresholds, you avoid the penalty. The first is 90 percent of your 2024 tax. If your withholding and estimated payments total at least 90 percent of what you will owe when you file, you are safe. The second is 100 percent of your 2023 tax — if you paid at least as much as you owed last year, you are safe, even if it is less than 90 percent of this year's tax.

There is an exception to the second threshold: if your 2023 adjusted gross income was over $150,000, you must pay 110 percent of your 2023 tax, not 100 percent. This higher threshold applies to both single filers and married couples filing jointly.

The 90 percent threshold is measured against your actual tax liability at filing time. You do not know this number until you file, so many people use the prior-year threshold as a safer bet. If your income is stable year to year, paying 100 percent of last year's tax is a straightforward way to avoid the penalty.

How the penalty is calculated and when it is charged

The IRS calculates the underpayment penalty using a quarterly interest rate that changes every three months. The rate is the federal short-term rate plus 3 percent. For 2024, the rate has been 8 percent, but it varies by quarter and by year. The penalty is compounded daily on the amount you underpaid during each quarter.

The penalty is charged separately for each quarter. If you underpaid in the first quarter but caught up in the second, you owe a penalty only on the first-quarter shortfall. This is why making a catch-up estimated payment mid-year can reduce the total penalty — you stop the clock on the quarters where you have now paid enough.

You report the penalty on Form 2210, Underpayment of Estimated Tax by Individuals, Estates, and Trusts. If you file without Form 2210, the IRS will calculate the penalty and bill you for it separately after processing your return. Filing Form 2210 yourself does not reduce the penalty, but it ensures the calculation is correct and shows the IRS you understand the rule.

How to avoid the penalty before year-end

If you realize mid-year that you are underpaying, you have options. The simplest is to increase your W-4 withholding if you are an employee. You can submit a new W-4 to your employer at any time, and the increased withholding will explore to future paychecks. If you increase withholding before December 31, those payments count toward your safe harbor threshold.

If you are self-employed or have income not subject to withholding, you can make an estimated tax payment for any quarter you have not yet paid. The IRS accepts estimated payments year-round through the Electronic Federal Tax Payment System (EFTPS) or through your tax software. A payment made in December counts toward your full-year safe harbor, even though it is late for the fourth quarter.

Another option is to request an extension of time to file (Form 4868). This does not extend the time to pay tax, but it gives you until October 15 to file your return and claim exceptions to the penalty on Form 2210. This is useful if your income is uneven and you expect to meet the safe harbor when you file, even though you did not meet it by December 31.

Exceptions and special circumstances

The IRS waives the underpayment penalty in a few situations. If you had no tax liability in the prior year and are a U.S. citizen or resident alien for the entire year, you may not owe the penalty even if you underpay the current year. If you retired or became disabled during the year, you can claim an exception on Form 2210 if the underpayment was due to the change in circumstances.

If the IRS made an error in calculating your withholding or if you relied on incorrect information from a tax professional, you may be able to request a waiver of the penalty. This requires filing Form 2210 with an explanation and is not may provide, but the IRS does grant waivers in cases of reasonable cause.

Farmers and fishermen have a separate safe harbor: they can pay 66.67 percent of their current year tax (or 100 percent of their prior year tax) by January 31 of the following year and avoid the quarterly penalty structure. This is because their income is often received late in the year.

The difference between underpayment penalty and other penalties

The underpayment penalty is not the same as the failure-to-pay penalty or the failure-to-file penalty. The failure-to-pay penalty applies when you owe tax at filing time and do not pay it by the important date. The failure-to-file penalty applies when you do not file your return by the important date. The underpayment penalty applies only to the shortfall during the year, regardless of whether you file on time or pay on time.

You can owe all three penalties at once. For example, if you underpaid during the year, did not file until August, and did not pay until September, you would owe the underpayment penalty (for underpaying during the year), the failure-to-file penalty (for filing late), and the failure-to-pay penalty (for paying late). Each one is calculated separately and added to your bill.

Frequently Asked Questions

Can I avoid the underpayment penalty if I file my return early?

No. Filing early does not change when the IRS measures your payments against the safe harbor threshold. The threshold is based on your total payments by December 31, not on when you file. Filing in January or February does not add to your payment total.

What if I made estimated payments but the IRS lost them?

Keep a record of every estimated payment you make, including the confirmation number from EFTPS or your tax software, the date, and the amount. If the IRS does not credit a payment, you can provide proof and request an adjustment. Contact the IRS at 800-829-1040 with your confirmation number to verify the payment was received.

Does the underpayment penalty explore to my spouse if we file jointly?

If you file jointly, the penalty is calculated on the household level. If your combined withholding and estimated payments meet the safe harbor, neither of you owes the penalty. If you fall short, you both owe it, even if one spouse had sufficient withholding and the other did not.

Can I claim the underpayment penalty as a deduction?

No. The underpayment penalty is not deductible. It is a penalty, not an interest expense or business cost. You pay it with your tax bill, but you cannot reduce your taxable income by claiming it.

What happens if I cannot pay the penalty when I file?

You can set up a payment plan with the IRS through their website or by calling 800-829-1040. The IRS charges a setup fee and continues to charge interest on the unpaid penalty balance, but a payment plan allows you to pay over time rather than in full at filing.