Supplemental Wage Tax Rates: How Bonuses, Commissions & Overtime Are Taxed

When an employee receives a performance bonus, commission check, or sign-on incentive, they are often stunned to see that their take-home payout is significantly smaller than expected. A common complaint among workers is: "My company taxed my bonus at 40% or 50%!"

In reality, bonuses are not taxed at a higher tax rate than regular wages. Under the Internal Revenue Code, all income earned from employment is treated as ordinary income subject to standard federal tax brackets.

However, the tax withholding rules governing supplemental wages require employers to use special withholding formulas that often deduct far more cash up front.

This comprehensive guide explains the IRS supplemental wage withholding rules, the difference between the 22% flat rate and the aggregate method, and how to "gross up" a bonus check.

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1. What Are Supplemental Wages According to the IRS?

Under IRS Treasury Regulation § 31.3402(g)-1, supplemental wages are defined as compensation paid to an employee in addition to their regular wages:

• Performance and year-end bonuses
• Sales commissions and incentives
• Overtime pay paid separately from regular wages
• Accumulated leave and PTO payouts
• Severance pay and golden parachutes
• Retroactive pay increases
• Signing and retention bonuses
• Taxable non-cash fringe benefits (e.g., company car personal use)

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2. The Two Federal Withholding Methods

Employers must choose one of two IRS-sanctioned methods when calculating federal income tax withholding on supplemental payments:

Method A: The Flat Percentage Method (Standard 22%)

If supplemental wages paid to an employee during the calendar year are $1 million or less, the employer can withhold federal income tax at a flat rate of 22%.

• Statutory Surtax Threshold: If supplemental wages exceed $1,000,000, any amount over $1 million is subject to mandatory federal withholding at the highest tax bracket: 37%.

Method B: The Aggregate Method

The employer combines the bonus with the employee's regular paycheck for the current pay period. The payroll software calculates withholding on the total sum using standard W-4 withholding tables, as if the employee earned that massive check every single pay period.

• The Problem: The aggregate method treats a single $5,000 quarterly bonus as if the worker earns an extra $130,000 per year, pushing the paycheck into high 24%, 32%, or 35% withholding brackets.

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3. Full Breakdown of a $10,000 Bonus Check

Even under the flat 22% federal rate, statutory payroll taxes quickly consume over a third of the gross bonus:

Tax Withholding Line Item	Statutory Rate	Deducted Amount
Gross Bonus Amount	—	$10,000.00
Federal Income Tax (Supplemental Flat Rate)	22.0%	-$2,200.00
Social Security Tax (OASDI)	6.2%	-$620.00
Medicare Tax (HI)	1.45%	-$145.00
State Income Tax (e.g., California Supplemental)	6.6%	-$660.00
Total Statutory Taxes Deducted:	36.25%	-$3,625.00
Net Cash Payout to Employee:	63.75%	$6,375.00

Calculate Net Bonuses: Calculate your net take-home pay or reverse-calculate a gross bonus using our free Bonus Tax Calculator.

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4. How to "Gross Up" a Bonus Check

Employers often want an employee to receive a clean net dollar figure (e.g., "We want Jane to receive exactly $5,000 in cash for her performance"). To do this, the company must gross up the bonus:

$$\text{Grossed-Up Bonus} = \frac{\text{Desired Net Pay}}{1 - \text{Total Statutory Tax Withholding Rate}}$$

Worked Gross-Up Example:

• Desired Net: $5,000
• Total Tax Rate (22% Fed + 7.65% FICA + 5% State = 34.65% = 0.3465): $$\text{Gross Required} = \frac{$5,000}{1 - 0.3465} = \frac{$5,000}{0.6535} = \mathbf{$7,651.11}$$

The employer cuts a payroll check for $7,651.11, remits $2,651.11 in mandatory withholdings to tax authorities, and Jane receives exactly $5,000.00 net.

Check tax brackets and marginal liability with our Tax Bracket Calculator and Hourly Paycheck Calculator.