Do I meet IRS safe harbor to avoid underpayment penalties?

Check whether you meet IRS safe harbor rules by comparing current-year tax, withholding, and prior-year tax. The tool evaluates the 90% and 100%/110% thresholds for 2025 or 2026 and shows any shortfall so you can adjust withholding or make estimated payments.

No login required.

How this calculation works

  • Compares current-year projected tax to withholding and estimated payments.
  • Checks 90% current-year and 100%/110% prior-year safe harbor thresholds.
  • Estimates the remaining amount needed to meet the safest threshold.

Common mistakes and caveats

  • Safe harbor thresholds can differ for high-income filers.
  • Actual penalties depend on timing of payments throughout the year.

FAQ

Does safe harbor mean I will owe no tax?

No. It only reduces underpayment penalties; you may still owe tax at filing.

Last updated & sources

Last updated January 15, 2026.

TaxGuide Pro provides free state and federal tax calculators for individuals, freelancers, and small businesses.