How to Gross Up Payroll: Formula, Combined Rate & Thresholds

To gross up payroll, divide the net amount you want the employee to receive by one minus the combined tax rate that applies to the payment. That single division scales the payment up so that federal withholding, FICA, and any state income tax consume exactly the difference, leaving the promised net in the employee’s account. The formula itself is one line. The work is picking the right rates.

The Formula

Gross Payment = Desired Net Pay ÷ (1 − Combined Tax Rate)

The denominator is the share of each dollar the employee actually keeps after taxes. Dividing by it produces the gross figure that, once run through payroll, leaves the target net behind.

Everything else in the calculation is figuring out what belongs in that combined rate.

Tax Rates That Go Into the Combined Rate

Before touching the formula, gather the percentages that apply to a supplemental payment for this specific employee:

Federal supplemental withholding — 22%. IRS Publication 15 sets a flat 22% federal income tax withholding rate on supplemental wages paid to any employee whose total supplemental pay for the calendar year is under $1 million.¹
Social Security — 6.2%. The employee owes 6.2% on wages up to the annual wage base.²
Medicare — 1.45%. The employee owes 1.45% with no wage cap.²
State and local income tax. Some states set a flat supplemental withholding rate; others require you to withhold at the employee’s regular bracket; several states have no income tax. Confirm the rate with your state revenue agency.

Add the applicable percentages together. The sum is the combined tax rate that goes into the denominator.

Worked Example: No State Income Tax

You want the employee to receive exactly $500 after taxes, and no state income tax applies. Combined rate: 22% + 6.2% + 1.45% = 29.65%. As a decimal that’s 0.2965, so the denominator is 1 − 0.2965 = 0.7035.

$500 ÷ 0.7035 = $710.73

Process $710.73 through payroll. Federal withholding takes $156.36, Social Security takes $44.07, and Medicare takes $10.30. The employee deposits $500.¹²

Worked Example: With a Flat State Supplemental Rate

Now assume a 5% state supplemental withholding rate. Combined rate: 22% + 6.2% + 1.45% + 5% = 34.65%. Denominator: 0.6535.

$500 ÷ 0.6535 = $765.11

Same $500 net, but the state tax adds $54.38 to the required gross. The higher the state rate, the more dramatic the gross-up.

Thresholds That Change Which Rates Apply

The rates above assume a mid-range employee whose wages haven’t crossed any tax breakpoints. Three thresholds can change what belongs in the combined rate, and missing one is where most gross-up errors happen.

Social Security Wage Base of $184,500 in 2026

Social Security tax only applies to the first $184,500 of wages in 2026.³ If the employee has already earned at or above that figure before the payment, drop the 6.2% from your combined rate. If they’re close to the cap, only the portion of grossed-up wages below $184,500 is subject to Social Security, and you’ll need to split the calculation. Get this wrong and you either overpay the gross-up or underpay and miss the promised net.

Additional Medicare Tax at $200,000

Once total wages for the year exceed $200,000, the employer must withhold an additional 0.9% Medicare tax on every dollar above that line.⁴ The employee-side Medicare rate becomes 2.35% on the excess. If a gross-up crosses that line, factor the higher rate into the portion above it. The employer does not pay a matching share of the additional 0.9%.

Supplemental Wages Over $1 Million

If total supplemental wages paid to a single employee during the calendar year exceed $1 million, federal withholding on the excess jumps from 22% to 37%.¹ The grossed-up amount itself counts as supplemental wages, so a large gross-up can push an employee past this line even if the net figure stays below $1 million. Run year-to-date numbers before committing to a gross-up for a highly compensated employee.

When the Simple Formula Falls Short

One division is enough when every applicable tax uses a flat rate. Federal supplemental withholding, Social Security, and Medicare all qualify. Two situations break the clean math.

First, not every state offers a flat supplemental withholding rate. Some require the aggregate method, which combines the bonus with regular pay and withholds at the resulting bracket. When withholding depends on a progressive bracket, one percentage won’t cover it. Payroll software solves this by iterating: it tests gross figures until the net matches the target. Doing it by hand means estimating the marginal bracket, running the formula, checking whether the gross actually lands in that bracket, and adjusting if it doesn’t.

Second, the formula assumes the payment doesn’t cross a wage cap. If the grossed-up amount pushes wages past the Social Security wage base or the $200,000 Medicare threshold, split the calculation: one rate below the threshold, a different rate above it. Check year-to-date wages before you start.

Employer Taxes Sit on Top of the Gross-Up

The formula covers the employee’s share of taxes only. The employer still owes its own taxes on the grossed-up wages, and those add to the total cost of the payment.

Employer FICA match. The company owes 6.2% Social Security and 1.45% Medicare on the grossed-up wages, subject to the same $184,500 Social Security wage base.²
Federal unemployment (FUTA). FUTA is 6.0% on the first $7,000 of each employee’s annual wages, reduced to an effective 0.6% for most employers who take the 5.4% state credit. If the employee has already earned more than $7,000 for the year, FUTA doesn’t apply to the gross-up.⁵
State unemployment (SUTA). State wage bases range from $7,000 to over $78,000, and employer rates vary by claims history. As with FUTA, the tax only applies if the employee is still below the state’s wage base.

Using the $710.73 example, the employer’s matching FICA adds about $54.40. Delivering that $500 net actually costs roughly $765 once employer taxes are counted. For large bonus programs, budget for the match across every employee.

Recording and Reporting the Payment

The grossed-up figure is the wage number that flows through every payroll record. Enter it as gross pay, not the promised net. Pay stubs, tax filings, and the general ledger all key off the gross.

On Form 941, the grossed-up wages go on Line 2 with the rest of the quarter’s wages, and the withholdings flow into the corresponding tax lines.⁶ There’s no separate line for grossed-up pay.

At year-end, the grossed-up amount appears in Box 1 of the W-2, with taxes withheld in Boxes 2, 4, and 6 for federal income tax, Social Security, and Medicare. The W-2 totals should reconcile to the quarterly 941 filings.

Withheld taxes follow the normal deposit schedule. Monthly depositors deposit by the 15th of the following month. Semi-weekly depositors owe deposits the following Wednesday for Wednesday-through-Friday paydays, and the following Friday for Saturday-through-Tuesday paydays. If a single payment accumulates $100,000 or more in tax liability within a deposit period, the deposit is due by the next business day.⁷ A large year-end bonus program can spike deposit obligations, so flag these payments in advance to avoid late-deposit penalties. All federal tax deposits must be made electronically.

When Employers Typically Gross Up

Cash bonuses are the obvious case, but several other payment types routinely get grossed up:

Relocation packages, since moving expense reimbursements are taxable income and grossing up keeps the employee from losing money on a company-directed move.
Taxable fringe benefits. When an employer pays the employee’s share of tax on certain fringe benefits, the tax payment itself has to be included in wages. Group-term life insurance coverage above $50,000 and personal use of a company vehicle are common examples.⁸
Sign-on bonuses, where a promised $10,000 that shrinks to $7,000 after withholding feels like a bait-and-switch.
Achievement awards, retirement gifts, and contest prizes, which are supplemental wages and would otherwise arrive smaller than intended.

1
Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
2
Social Security Administration. Social Security Tax Rates
3
Social Security Administration. What Is the Current Maximum Amount of Taxable Earnings for Social Security?
4
Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
5
Internal Revenue Service. Topic No. 759, Form 940, Employers Annual Federal Unemployment (FUTA) Tax Return
6
Internal Revenue Service. Instructions for Form 941 (03/2026)
7
Internal Revenue Service. Employment Tax Due Dates
8
Internal Revenue Service. Publication 15-B Employer’s Tax Guide to Fringe Benefits