Supplemental Wage Tax Calculator

About the Supplemental Wage Tax Calculator

Supplemental wages are payments made to employees outside of their regular salary or hourly pay. The IRS classifies bonuses, commissions, overtime pay, severance pay, back pay, retroactive pay increases, taxable fringe benefits, and certain prizes as supplemental wages, each subject to special withholding rules.

For federal purposes, employers may withhold at a flat 22% rate on supplemental wages up to $1 million per calendar year. Amounts exceeding $1 million trigger the 37% rate. Alternatively, the aggregate method combines supplemental and regular wages to calculate withholding using standard tax tables. State supplemental wage rates vary widely, from 0% in states with no income tax to over 13% in California.

This Supplemental Wage Tax Calculator covers all types of supplemental pay. Enter the payment amount, select the pay type for reference, and specify your state rate to see the complete tax breakdown including federal withholding, state tax, Social Security, and Medicare. Payroll professionals can use this to verify withholding on any supplemental payment type.

When This Page Helps

Different types of supplemental pay can trip up even experienced payroll professionals. This calculator applies the correct federal flat rate, accounts for the $1M threshold, adds state supplemental rates, and computes FICA—providing a single tool for all supplemental wage withholding calculations regardless of pay type.

How to Use the Inputs

1. Enter the supplemental wage amount.
2. Select the type of supplemental pay (bonus, commission, severance, overtime, other).
3. Enter your state's supplemental wage tax rate.
4. Enter year-to-date supplemental wages to determine if the $1M threshold applies.
5. Review the complete tax breakdown and net payment.
6. Adjust amounts to model different payment scenarios.

Example Calculation

Tips & Best Practices

• The $1M threshold for the 37% rate applies to cumulative supplemental wages per calendar year, not per payment.
• Commissions paid on a regular schedule may be treated as regular wages for withholding at the employer's discretion.
• Severance pay is supplemental wages and subject to FICA in addition to income tax withholding.
• State supplemental rates: CA 10.23%, NY 11.7%, PA 3.07%, IL 4.95%, TX/FL/WA 0%.
• If supplemental wages are not separately identified from regular pay, the aggregate method must be used.
• Overtime premium pay qualifies as supplemental wages and can use the flat 22% withholding rate.

Federal Supplemental Wage Withholding Methods

The IRS provides two approaches for withholding on supplemental wages. The percentage method withholds a flat 22% on amounts up to $1 million and 37% on the excess. This is simple and predictable. The aggregate method treats the supplemental payment as if it were paid with regular wages in a single pay period, potentially resulting in higher withholding for employees with high regular pay.

State-by-State Supplemental Rates

State supplemental wage rates vary significantly. California withholding on supplemental wages is 10.23% for amounts up to $1 million and 13.3% above that. New York uses 11.7%, while Illinois applies its flat rate of 4.95%. Understanding your state's specific rules is essential for accurate payroll processing.

Best Practices for Payroll Teams

Maintain a reference table of current federal and state supplemental wage rates. When processing multiple types of supplemental pay in a single pay period, track cumulative supplemental wages against the $1M threshold. Document the withholding method used for each payment type for audit purposes.

Frequently Asked Questions

• What types of pay are supplemental wages?

  The IRS classifies the following as supplemental wages: bonuses, commissions, overtime pay, severance pay, back pay, retroactive pay increases, accumulated sick leave payouts, taxable fringe benefits, moving expense reimbursements, and non-deductible employee expense reimbursements. Keeping this factor in mind will improve the accuracy and usefulness of your overall calculations.

• Is the 22% rate a final tax rate?

  No. The 22% flat rate is a withholding rate, not the final tax rate. Your actual tax liability depends on your total annual income and tax bracket. The difference between withholding and actual liability is reconciled on your annual tax return via a refund or balance due.

• When does the 37% rate apply?

  The 37% mandatory withholding rate applies to supplemental wages exceeding $1 million in a calendar year from the same employer. All supplemental payments up to $1 million use the 22% flat rate (or aggregate method).

• Can an employer choose different methods for different pay types?

  Employers generally apply the same withholding method consistently. However, the flat rate method can only be used when supplemental wages are paid separately from (or specifically identified within) regular wages. If they're not identified separately, the aggregate method must be used.

• Are supplemental wages subject to FICA?

  Yes. Social Security (6.2% up to the wage base) and Medicare (1.45% with no cap) apply to all supplemental wages. The additional 0.9% Medicare tax applies when combined wages exceed $200,000.

• How do states handle supplemental wage withholding?

  States with income tax either specify a flat supplemental rate, require the use of standard withholding tables, or follow the federal approach. Rates range from about 3% to over 13%. Nine states with no income tax (TX, FL, WA, NV, WY, SD, AK, TN, NH) impose no state supplemental withholding.

• Is overtime considered supplemental wages?

  Yes, overtime pay (the premium portion and sometimes the total overtime amount) is classified as supplemental wages. Employers can use the flat 22% rate for the overtime premium or combine it with regular pay under the aggregate method.

• What about stock options and RSU vesting?

  The taxable amount from exercising stock options or RSU vesting is treated as supplemental wages. Federal withholding at 22% (or 37% above $1M) applies, plus applicable state and FICA taxes.