What This Calculator Estimates
Enter a gross bonus and your own withholding-rate assumptions to get an estimated after-withholding bonus. The calculator accepts federal, state, local, Social Security, Medicare, and additional Medicare rates, then applies each as a flat percentage of the full bonus. The interface calls the output Estimated after-tax bonus; here, that means after the modeled withholding, not final annual tax liability.
How the Calculation Works
The calculator adds all six entered rates, calculates withholding from that combined rate, and subtracts the result from the gross bonus:
Total withholding rate = Federal % + State % + Local % + Social Security % + Medicare % + Additional Medicare %
Withholding amount = B x (Total withholding rate / 100)
After-tax bonus = B - Withholding amount
For example, a $5,000 bonus with 22% federal, 6.2% Social Security, and 1.45% Medicare withholding (29.65% combined) has a withholding amount of $1,482.50 and an estimated after-tax bonus of $3,517.50.
How to Use the Calculator
- Enter a value greater than 0 in Gross bonus amount ($).
- Review or edit the pre-filled Federal supplemental withholding rate (%), Social Security withholding rate (%), and Medicare withholding rate (%).
- Optionally enter State withholding rate (%, optional), Local / other withholding rate (%, optional), and Additional Medicare surtax rate (%, optional). A blank optional field is treated as 0%.
- Select Calculate. The result section stays hidden until validation succeeds.
- Review the statistics, formula, and assumptions table. Use Copy result or Download result (.txt) to save the plain-text result.
- Select Reset to clear the bonus, optional rates, errors, and result, and restore the default required rates.
Validation and Displayed Values
The gross bonus must be greater than 0. Required rates must be present and between 0 and 100; entered optional rates must also be between 0 and 100. The combined withholding rate cannot exceed 100%. A failed check shows a specific error and hides the previous result. Blank optional rates appear as 0.00% in the result and downloaded text.
Limitations and Data Scope
The calculation uses the numbers entered into the tool. It does not fetch live tax tables, payroll records, or account data. It does not model progressive tax brackets, aggregate withholding, wage-base limits reached during the year, benefit deductions, or personalized annual tax liability. Its default rates are static editable assumptions, not verified live tax data. The result is not an official pay stub or personalized tax or financial advice.
Frequently Asked Questions
How is a bonus taxed compared to regular pay?
This calculator does not determine how your employer or tax authority must withhold a bonus. It applies the six rates you enter as flat percentages of the full bonus and reports an estimated after-withholding amount, not final tax liability.
What withholding rates should I enter?
Review the pre-filled federal supplemental, Social Security, and Medicare rates, then replace them with the rates you want to model. Add state, local, or additional Medicare rates when applicable. The defaults are editable static assumptions, not live tax data.
Does this calculator fetch my actual tax rate or payroll data?
No. The calculator uses the bonus amount and withholding rates you type in. It does not fetch live tax tables, payroll records, or account data, and it is not personalized tax or financial advice.
Why might my actual bonus paycheck differ from this estimate?
Your paycheck can differ because this calculator applies each entered rate to the full bonus and does not model payroll methods, progressive brackets, wage-base limits reached during the year, benefit deductions, or other withholding factors.
Is withholding the same as my final tax bill?
No. The result is an estimate of withholding based on the rates you enter. It does not calculate your final annual tax liability or tell you whether you will receive a refund or owe more.