To avoid the federal underpayment penalty, your total withholding for the year needs to cover at least one of two amounts: 90% of the tax you’ll owe for the current year, or 100% of the total tax on last year’s return. If your prior-year adjusted gross income was over $150,000, that second target rises to 110%. Hit either benchmark and you’re protected, no matter how large your final balance due turns out to be. That is how much withholding you need to avoid a penalty, and everything below is the detail around those three numbers.
The Two Safe Harbor Targets
The IRS won’t charge an underpayment penalty if your total withholding and estimated payments for the year hit at least one of two thresholds.1Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty You pick whichever is easier to meet.
90% of This Year’s Tax
If your payments through withholding total at least 90% of the tax on your current-year return, no penalty applies.2Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual to Pay Estimated Income Tax The catch is that you’re aiming at a number you won’t know for certain until you file. A late-year income spike or a deduction that falls through can leave you short. This target works best when your income is predictable.
100% of Last Year’s Tax
Your second option is to pay at least 100% of the total tax shown on last year’s return.2Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual to Pay Estimated Income Tax This is the easier number to hit because you already know it when the year starts. For the 2026 tax year, look at the total tax line on your 2025 Form 1040 (starting from line 24, reduced by refundable credits).3Internal Revenue Service. 2025 Instructions for Form 1040 Cover that figure through withholding and you’re protected even if this year’s income doubles.
Two situations knock out this safe harbor. Your prior-year return has to have covered a full 12-month period, and you have to have filed one at all.2Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual to Pay Estimated Income Tax Fail either and you’re limited to the 90% current-year test.
110% If Your Prior-Year AGI Was Over $150,000
If the adjusted gross income on last year’s return exceeded $150,000, the prior-year target jumps from 100% to 110%. For married taxpayers filing separately, the threshold is $75,000.2Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual to Pay Estimated Income Tax So if your 2025 AGI was $200,000 and your 2025 total tax was $40,000, you’d need at least $44,000 withheld during 2026 to qualify.
This rule catches people off guard because the trigger is last year’s income. Even if you expect to earn less this year, the 110% requirement is already locked in by what happened last year. The 90% current-year target, by contrast, stays at 90% no matter what you earn.
Setting Your W-4 to Hit the Target
Form W-4 is the tool that tells your employer how much federal tax to pull from each paycheck.4Internal Revenue Service. About Form W-4, Employee’s Withholding Certificate For penalty avoidance, the field that matters most is Step 4(c), labeled Extra Withholding. That line lets you specify a flat dollar amount to add to every paycheck on top of the standard calculation.
The math is straightforward:
- Pick your safe harbor target (say, 110% of last year’s tax).
- Estimate what your standard withholding will cover over the full year.
- Subtract to find the gap.
- Divide by the number of pay periods you have left.
- Enter that amount on Step 4(c) and submit the new W-4 to payroll.
The IRS Tax Withholding Estimator can run these projections using your year-to-date pay stubs.
Why Withholding Beats Estimated Payments for Fixing Shortfalls
Tax withheld from wages is treated as if it were paid in equal installments across all four quarterly due dates, regardless of when it actually came out of your check.5Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual to Pay Estimated Income Tax This is a real advantage. If you notice in November that you’re badly short, submit a new W-4 with a large Step 4(c) amount for your remaining paychecks. December withholding gets spread across all four quarters for penalty purposes, retroactively curing earlier shortfalls. Estimated tax payments don’t get this treatment; they only count for the quarter in which they’re actually paid.
Watch Bonuses and Supplemental Wages
Employers withhold federal income tax on bonuses, commissions, and other supplemental wages at a flat 22% rate when your total supplemental pay for the year stays at or below $1 million. Anything over that gets withheld at 37%.6Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide If your marginal rate is higher than 22%, a large bonus can look fully taxed on the pay stub while actually leaving you short at filing time. Fold bonus withholding into your safe harbor math instead of assuming the employer took enough.
If You Also Have Self-Employment Income
Your safe harbor target is your total federal tax bill, not just income tax. Self-employed earnings also carry self-employment tax at 15.3% on net earnings up to the Social Security wage base of $184,500 for 2026, with the 2.9% Medicare portion continuing above that with no cap.7Social Security Administration. Contribution and Benefit Base Withholding from a W-2 job can cover this, but only if you dial up Step 4(c) high enough to absorb it. Otherwise you’ll need quarterly estimated payments on Form 1040-ES to close the gap.8Internal Revenue Service. About Form 1040-ES, Estimated Tax for Individuals
When No Penalty Applies Even If You Miss
Several statutory exceptions eliminate the penalty even if you fall short of both safe harbors.
You Owe Less Than $1,000
No penalty applies if the tax on your return, minus withholding and refundable credits, comes to less than $1,000.2Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual to Pay Estimated Income Tax This is the most commonly triggered exception and covers people whose withholding gets them close but not all the way to a safe harbor.
You Owed Zero Tax Last Year
If your prior-year tax liability was zero, you filed a return covering a full 12-month period, and you were a U.S. citizen or resident throughout, no penalty applies for the current year.2Office of the Law Revision Counsel. 26 USC 6654 – Failure by Individual to Pay Estimated Income Tax
Retirement, Disability, or Disaster Waivers
The IRS can waive the penalty if you retired after reaching age 62 or became disabled during the tax year or the year before, and the underpayment was due to reasonable cause. It can also waive the penalty when a casualty, disaster, or other unusual circumstance caused the shortfall.1Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty Claim either waiver by checking the appropriate box in Part II of Form 2210, attaching documentation, and filing it with your return.9Internal Revenue Service. 2025 Instructions for Form 2210
State Rules Are Separate
Meeting the federal safe harbor won’t protect you from a state underpayment penalty. Most states with an income tax run their own version, with trigger thresholds and safe harbor percentages that vary. Some mirror the federal framework closely; others don’t. Check your state’s department of revenue before assuming that federal-level protection carries over.