Did you know that even if your foreign income is fully taxed abroad and offset by a foreign tax credit, you could still owe thousands more in U.S. taxes?
This blog explains how foreign income affects U.S. taxes. It’s not because the U.S. is double-taxing the same income — it’s because that foreign income may raise your total taxable income enough to push your domestic earnings into a higher tax bracket.
That ripple effect leads to a bigger U.S. tax bill than expected — even when your foreign income seems “taken care of.”
Why Does Foreign Income Increase Your U.S. Tax Bill?
When foreign income (like RSUs) is added to your total taxable income, it raises your overall income level and may increase your federal effective tax rate.
Even though the foreign income itself may be offset by a foreign tax credit, your U.S. income — like your wages — gets taxed at that higher rate, leading to a surprise balance due.
The Scenario: RSUs Received After Relocation
In 2023, a U.K. citizen moved to New York City for work. In 2024, their income included:
- U.S. salary: $255,700
- UK RSU income: $80,000 — earned before the move, exercised and paid out in 2024
- Taxable state refunds: $3,636
Note: RSUs, or Restricted Stock Units, are a form of equity compensation. They’re typically awarded during employment and become taxable upon vesting or exercise.
Tax Summary:
- UK withheld: $24,000 in tax (30%)
- U.S. employer withheld: $50,827 in federal income tax (~19.88%)
How Is U.S. Tax on the RSUs Calculated?
Once U.S. tax residency begins, worldwide income — including post-move RSU payouts — becomes taxable.
With the RSUs added, the taxpayer’s federal effective tax rate rose to 24.76 percent:
$80,000 × 24.76% = $19,770 in U.S. federal tax
Foreign Tax Credit — Did It Cover U.S. Tax on the RSUs?
Yes — the credit fully offset the tax on the foreign RSU income.
| Income Type | Amount | U.S. Tax Owed | UK Tax Paid | Credit Allowed |
|---|---|---|---|---|
| RSUs | $80,000 | $19,770 | $24,000 | $19,770 |
The remaining $4,230 in UK tax was carried forward for use in future years.
The Catch: Higher Tax on U.S. Wages
Even though no U.S. tax was owed on the RSUs, adding them to the return increased total taxable income — pushing U.S. wages into a higher bracket.
Here’s how the federal return played out:
| Source | Income | Federal Tax | Medicare Tax | Total Tax | Fed Withheld | Foreign Tax Credit | Balance Due |
|---|---|---|---|---|---|---|---|
| U.S. Salary | $255,685 | $63,304 | $628 | $63,932 | ($50,827) | — | $13,105 |
| UK RSUs | $79,849 | $19,770 | — | $19,770 | — | ($19,770) | $0 |
| State Refunds | $3,636 | $900 | — | $900 | — | — | $900 |
| Total | $339,170 | $83,974 | $628 | $84,602 | ($50,827) | ($19,770) | $14,005 |
Had the RSUs not been received, the balance due would have been around $5,814. In this case, RSU income indirectly added $8,191 in federal tax liability.
State Tax — A Second Surprise
New York does not allow a foreign tax credit. So despite being taxed abroad, the RSUs were taxed again at the state level:
| Source | Income | NY Tax | NYC Tax | Total State Tax | State Withheld | NYC Credit | Balance Due |
|---|---|---|---|---|---|---|---|
| U.S. Salary | $255,685 | $17,097 | $9,579 | $26,675 | ($28,626) | ($740) | ($2,691) |
| UK RSUs | $79,849 | $5,339 | $2,991 | $8,331 | — | — | $8,331 |
| Total | $335,534 | $22,436 | $12,570 | $35,006 | — | — | $5,640 |
In states with no income tax — like Texas or Florida — this layer of surprise wouldn’t apply, but the federal impact remains.
Does This Affect Everyone the Same Way?
The higher your income, the more dramatic this effect can be. Those already near the top of a tax bracket may be pushed into a significantly higher tier when foreign income is added.
That means even fully credited income can amplify your overall liability — simply by changing what bracket your domestic wages fall into.
Planning Tips to Avoid Surprises
Expecting RSU payouts or other foreign income this year? Here’s what to do:
- Submit an updated Form W-4 to increase federal withholding
- Make quarterly estimated payments: April 15, June 15, September 15, January 15
- Evaluate your projected tax position mid-year to avoid underpayment penalties (typically around 7 percent)
Proactive planning gives you time to adjust and reduces the risk of surprise bills during tax season.
Final Takeaway
Foreign tax credits eliminate double taxation on foreign income — but they don’t prevent foreign income from affecting how much tax you pay on your U.S. salary.
For newly arrived taxpayers receiving RSUs or other international compensation, understanding how foreign income affects U.S. taxes is critical if you’ve moved to the U.S. and expect compensation from abroad. Even when a foreign tax credit applies, the broader tax impact may catch you off guard.