Trump’s proposed tax changes could sharply raise costs for globally mobile US employees and businesses

Sweeping tax reforms proposed by President Donald Trump in his so-called “One, Big, Beautiful Bill” could significantly increase the costs associated with global mobility for US-based employers and internationally mobile employees, according to audit and advisory firm Blick Rothenberg.

Among the headline changes is a proposed incremental tax hike on income earned by residents of countries with “unfair tax regimes”, starting at 5% and rising to 20%. The implications for multinational companies and globally mobile individuals could be substantial — especially without forward planning.

“This isn’t just a headline change — it’s a significant concern for global employers and employees,” said David Livitt, Partner at Blick Rothenberg.

Who could be affected?

The proposed changes would affect a wide range of internationally connected individuals and businesses, including:

• Former US residents with US-sourced income: Those who continue to receive bonuses, stock payouts, or deferred compensation after leaving the country may face higher tax rates, despite no longer being resident.
• Employees on tax equalisation plans: These plans, common in global mobility programs, ensure the employer covers the tax bill for overseas assignments. If tax rates go up, assignment costs increase — potentially undermining the viability of future international postings.
• Employees moving to the US mid-year: People relocating to the US partway through the year may not gain full tax residency immediately, exposing part-year income to higher tax rates.
• Employees leaving the US at year-end: Those who depart during a tax year might find income earned post-departure, such as stock vesting or bonuses, taxed at elevated rates.

“These rules mean individuals could be taxed more harshly simply based on the timing of income — or where they live when it’s paid,” Livitt explained. “In many cases, it’s the employer who foots the bill through tax equalisation.”