Grossing up, also known as a “net-to-gross calculation,” is typically used when an employer wants to make sure an employee receives a specific dollar amount after taxes for a one-time payment such as a bonus, moving reimbursement, relocation assistance, or another taxable fringe benefit. Because these payments are generally treated as taxable wages, the employee may receive less than expected unless the employer increases the gross amount to offset withholding taxes. Federal guidance continues to treat supplemental wages as taxable wages subject to withholding rules.

How It Differs from Standard Payroll

Under a normal payroll process, you begin with gross wages, calculate applicable withholdings, and arrive at net pay. Grossing up works in reverse. Instead of starting with gross wages, you first decide how much net pay you want the employee to receive, and then you work backward to estimate the gross payment required to produce that result after taxes are withheld. This approach is commonly used for supplemental wage situations where the employer wants to cover some or all of the employee’s tax burden.

The Gross-Up Concept and Calculation

What Is the Gross-Up Rule?

The “gross-up” concept is a payroll practice in which an employer increases the gross amount of a payment to help cover the taxes the employee will owe on that payment. The goal is to ensure that the employee receives a specific net amount after withholding. Employers often use gross-ups for bonus payments, signing incentives, relocation benefits, and other one-time taxable payments.

Although there is no single formal IRS rule called the “gross-up rule,” gross-up calculations are widely used in payroll administration when handling supplemental wages and taxable fringe benefits.

How Do You Calculate a Gross-Up?

A simple way to think about gross-up math is with this formula:

Gross Pay = Net Pay ÷ (1 − Total Estimated Tax Rate)

In practice, the “total estimated tax rate” may include several components, such as:

Federal supplemental income tax withholding
Social Security tax
Medicare tax
Additional Medicare tax, when applicable
Massachusetts state income tax withholding

For federal supplemental wages, the IRS continues to use a 22% withholding rate for supplemental wages up to $1 million during the calendar year, and 37% for supplemental wages above that threshold. Social Security remains 6.2% up to the 2026 wage base of $184,500, and Medicare remains 1.45% on all covered wages.

Massachusetts generally applies a flat 5.0% withholding rate on wages. However, for high-income earners, an additional 4.0% surtax applies to taxable income above the annual surtax threshold (often referred to as the “millionaire tax”). Because of this, the effective tax rate for some supplemental payments may be higher depending on the employee’s year-to-date earnings.

Because Massachusetts uses a mostly flat tax structure with an additional surtax for high-income situations, the state portion of a gross-up estimate is simpler than in fully progressive-tax states, but still requires consideration of whether the surtax threshold has been reached.

Example of a Gross-Up Calculation

Suppose an employer wants an employee to receive a $700 net payment after taxes. To estimate the correct gross-up, the employer must account for federal withholding, FICA taxes, Medicare, possible Additional Medicare, and Massachusetts state withholding.

For most employees, Massachusetts withholding is based on the standard 5.0% rate. However, if the employee’s year-to-date wages plus the current payment exceed the surtax threshold, a portion of the payment may also be subject to the additional 4.0% surtax.

Actual withholding may vary depending on employee-specific factors, filing status, payroll setup, year-to-date wages, and Massachusetts withholding elections, so many employers prefer using payroll software or a calculator rather than working through the math manually.

The idea is the same regardless of the amount:

Start with the desired net payment
Estimate all applicable withholding taxes
Work backward to determine the gross payment needed
Verify that the resulting net pay is close to the intended amount

Common Scenarios for Net-to-Gross Pay

Incentives for New Hires

A signing bonus can help attract a strong candidate, but taxes may significantly reduce the amount the employee actually receives. A gross-up helps ensure the employee receives the intended net amount after withholding, which can improve transparency and create a better first impression.

Commission-Based Pay

Commissions can result in higher-than-expected withholding, which may surprise employees. Employers may choose to gross up commission payments to ensure employees receive a targeted after-tax amount tied to performance.

Relocation Expenses

Relocation-related payments are another common gross-up scenario. If an employer wants to reimburse a new hire for moving or transition costs and ensure the employee receives the full intended amount after taxes, grossing up the payment may help accomplish that goal. IRS guidance on fringe benefits and supplemental wages is relevant to these types of taxable payments.

Grossing Up a Relocation Payment Example

Let’s say your business hires an employee who must relocate to Massachusetts or move within the state to accept a new role. To assist with the transition, you offer a one-time taxable payment of $5,000 intended to cover moving-related expenses.

If you simply issue a $5,000 payment, the employee may receive less after federal, FICA, Medicare, and Massachusetts withholding are applied. By grossing up the payment, you can calculate the higher gross amount needed so that the employee’s final net amount is still approximately $5,000.

This approach helps ensure the employee receives the full intended benefit while keeping payroll calculations aligned with tax requirements.

Final Considerations for Grossing Up

Employers should remember that gross-up calculations include more than just federal withholding. They may also involve Social Security, Medicare, Additional Medicare, and Massachusetts state income tax withholding. Massachusetts uses a flat 5.0% withholding rate for most wage scenarios, with an additional 4.0% surtax applied only to income above the annual threshold. This means the state portion of a gross-up estimate is generally more straightforward than in many progressive-tax states, but still requires attention for higher-income employees.

Actual payroll results may still vary depending on filing status, withholding elections, year-to-date wages, payroll timing, and whether the surtax threshold is exceeded.

Drawbacks of Mishandling Gross-Ups

If a gross-up is calculated incorrectly, it can create additional work and employee dissatisfaction. Potential issues include:

Extra work for payroll or accounting staff
Employees receiving less than expected
Incorrect payroll reporting
The need to correct filings or address compliance issues

Get Grossing Up Right

Grossing up a payment—whether done manually or with a Massachusetts net-to-gross calculator—helps ensure employees receive a specific after-tax amount for bonuses, commissions, relocation reimbursements, or other supplemental wages.

By accounting for federal withholding, FICA taxes, Medicare, Additional Medicare, and Massachusetts state withholding, employers can estimate the correct gross payment while maintaining payroll accuracy. For 2026, the federal supplemental withholding framework remains 22% up to $1 million and 37% above that, the 2026 Social Security wage base is $184,500, and Massachusetts withholding generally uses a 5.0% rate with an additional 4.0% surtax applied only when income exceeds the annual threshold.

This calculator is designed to provide a helpful estimate for Massachusetts payroll scenarios in 2026. Actual payroll results may vary depending on employee-specific details, payroll timing, surtax applicability, and how the payment is processed. If you need help reviewing a gross-up calculation or managing payroll, the Beyond HCM team is available to assist.