Bonus Tax Calculator helps taxpayers turn a common tax question into a planning estimate. This guide explains the inputs, the main formula, and when to move from an estimate to official IRS forms or professional advice.
Table of contents
What the calculator estimates
Estimate how much of a bonus may be withheld for federal supplemental wages, Social Security, Medicare, and Additional Medicare tax. This is useful before a bonus, commission, severance, or award payment hits payroll.
The page is built for quick planning around paycheck and payroll taxes, with source links and a disclaimer so users understand the scope.
Inputs that matter most
The most important inputs are bonus amount, year-to-date wages, filing status. Small changes to these inputs can change the estimate, especially when a threshold or cap applies.
Use realistic annual numbers whenever possible and keep personal return details out of the browser if you are on a shared device.
How the formula works
Apply the IRS supplemental wage flat withholding rate, use the higher supplemental rate only for bonus dollars above the annual $1 million supplemental wage threshold, then estimate employee FICA using the Social Security wage base and Medicare rates.
The calculator keeps year-specific rates and limits in the shared annual limits file so January updates are easier to review.
When to use related tools
After using this page, related calculators such as Paycheck-calculator, Fica-tax-calculator, W4-withholding-calculator can help connect the estimate to withholding, deductions, or tax-season planning.
The goal is a practical next step, not a final tax return calculation.
Is bonus withholding the same as final tax?
What federal rate does this use?
Does this include state tax?
Why enter year-to-date wages?
Who should use this tool?
Go hands-on with the calculator
Estimate how much of a bonus may be withheld for federal supplemental wages, Social Security, Medicare, and Additional Medicare tax. This is useful before a bonus, commission, severance, or award payment hits payroll.
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