A gross-up is a calculation used to deliver a specified after-tax amount. Tax equalization is an employer policy that allocates assignment-related tax costs between the company and the employee.
They are related, but they serve different purposes.
What Is a Gross-Up?
A gross-up works backward from a target net payment to determine the required gross compensation.
When an employer pays an employee’s income tax, that payment generally creates additional taxable compensation. The calculation must therefore account for the tax on the employer-paid tax as well. Reference: IRS, Determining Employment Tax Liability
For example, assuming a flat 25% tax rate and a target net payment of $10,000:
Gross compensation = $10,000 ÷ (1 − 25%) = approximately $13,333
After approximately $3,333 of tax, the employee receives $10,000.
This simplified example excludes graduated rates, state and local taxes, Social Security and Medicare taxes, deductions, and other factors. Payroll withholding may also differ from the final tax liability. Reference: IRS, Supplemental Wage Gross-Up Example
What Is Tax Equalization?
Tax equalization generally aims to keep an employee’s covered tax burden comparable to what it would have been without the international assignment.
The employee typically bears a hypothetical tax, or hypo tax, based on a home-country calculation. The employer bears the actual taxes covered by its policy, with subsequent settlement adjustments.
Hypo tax is an amount used in the employer–employee arrangement; it is not itself the tax remitted to a tax authority. Reference: IRS Memorandum Discussing Tax Equalization and Hypothetical Tax
How Do They Work Together?
| Feature | Gross-Up | Tax Equalization |
|---|---|---|
| Function | Calculates gross compensation | Establishes tax cost allocation |
| Main objective | Delivers a specified net amount | Adjusts assignment-related tax differences |
| Key inputs | Taxable pay, rates, deductions | Covered income, taxes, and settlement rules |
A gross-up may implement the employer’s obligations under a tax equalization policy. However, an employer can also gross up a particular bonus or allowance without adopting tax equalization.
What Should the Policy Address?
Companies should clarify:
- Covered salary, bonuses, and assignment benefits
- Treatment of spousal, investment, and rental income
- Covered income taxes and social taxes
- Allocation of refunds and foreign tax credit benefits
- Arrival-year, departure-year, and post-assignment settlements
The policy should be established before calculating payroll. Tax return liabilities and employer–employee settlements should be tracked separately.
How We Can Help
Threefold Hara CPA assists with expatriate gross-up calculations, payroll processing, payroll tax returns, and individual income tax returns, taking the company’s policy and compensation arrangements into account.
This article provides general information. Treatment depends on the employer’s policy, contractual arrangements, applicable tax law, and individual circumstances.
Information reviewed: October 15, 2026
