Employee relocation is a powerful tool for filling critical roles, expanding into new markets, and supporting career development. But relocation benefits come with a hidden challenge: taxes. Since most relocation costs are considered taxable income, employees may end up with a far smaller net budget for approved benefits than expected—or even an unwelcome tax bill.
That’s where gross-up comes in. For HR leaders, building the right gross-up policy is not just about payroll math—it’s about fairness, compliance, and employee experience.
What Is Gross-Up?
Gross-up is the process of minimizing the employee’s tax liability, so the employee nets the full intended value of the benefit.
Since the gross-up itself is also taxable, the calculation must consider the “tax-on-tax” effect. If done correctly, the employee keeps the full promised benefit, while the employer avoids creating resentment or stress during a high-stakes move.
Why Gross-Up Matters to HR
- Talent Attraction & Retention: A relocation package that delivers its full value is a competitive advantage.
- Employee Trust: Moving is stressful—covering taxes shows your company supports employees holistically.
- Equity Across the Workforce: Without gross-up, employees in higher tax brackets lose more of their benefit.
- Compliance & Risk Management: Properly grossing up reduces the chance of payroll errors, W-2 corrections, or disputes.
Methods of Gross-Up
HR teams typically use one of three approaches:
- Flat Method
- Adds a fixed percentage to taxable expenses.
- Easiest to calculate but does not account for taxes on the gross-up itself.
- Supplemental / Inverse Method
- Formula:
- Uses IRS supplemental withholding rates for federal taxes: 22% in 2025 (up to $1M), 37% for amounts above $1M.
- Covers tax-on-tax, more accurate than flat, but based on assumed rates rather than each employee’s actual bracket.
- Marginal / Inverse Method
- Based on the employee’s actual income and tax bracket.
- Most precise and equitable; often paired with a year-end true-up to align with actual liability.
- Requires more coordination across HR, payroll, and finance.
Example
If an employee receives $30,000 in taxable relocation expenses and the assumed combined tax rate is 35%:
- Flat: $30,000 × 0.35 = $10,500 → Total $40,500
- Supplemental / Inverse: $30,000 ÷ (1 – 0.35) – $30,000 = $16,154 → Total $46,154
- Marginal / Inverse (40%): $30,000 ÷ (1 – 0.40) – $30,000 = $20,000 → Total $50,000
This demonstrates how the choice of method directly affects both employer costs and employee outcomes.
HR Best Practices for 2025
- Select a Method Aligned with Your Strategy
- Flat for simplicity, inverse for accuracy, marginal/inverse for fairness.
- Incorporate IRS Updates
- Use the current 22% supplemental rate for 2025 for federal tax assumptions (37% over $1M).
- Include All Relevant Taxes
- Don’t forget state, local, and payroll (Social Security/Medicare) taxes.
- Consider Year-End True-Ups
- Adjust benefits to match actual employee tax filings for fairness and compliance.
- Document Clearly
- Employees should understand if their package is grossed up, which method is used, and whether true-up applies.
- Coordinate Across Departments
- HR, payroll, and finance must work together—or partner with relocation/mobility providers—for accurate execution.
Final Takeaway
A relocation gross-up policy is more than a payroll adjustment—it’s a strategic HR tool. By choosing the right method, applying current IRS rates, and communicating transparently, HR leaders can protect employees from tax surprises while ensuring the company gets full value from its relocation investment.
Done right, gross-up builds trust, strengthens offers, and reinforces your organization’s reputation as a fair and supportive employer.
To learn more about this and other best practices for your global mobility program, contact MoveCenter.
