UK vs. U.S. Taxes for Expats: Rates, Key Differences, and How to Avoid Double Tax
The UK and the U.S. tax the same things, income, gains, and wages, but on opposite principles: the UK taxes you on where you live, the U.S. on your citizenship. For an American in the UK, that means both countries can claim the same income. UK rates are generally higher than U.S. rates across most income levels, so after the Foreign Tax Credit, most Americans in the UK owe the IRS nothing. This guide compares the two systems side by side, category by category, so you can see exactly where they differ and which one taxes more.
The short version of how they compare:
- Basis: the UK taxes by residency; the U.S. taxes by citizenship, worldwide, wherever you live.
- Rates: The UK generally taxes income and gains more heavily than the U.S.
- Tax year: the UK runs from April 6 to April 5; the U.S. runs from January 1 to December 31.
- The result: because UK tax is usually higher, the Foreign Tax Credit typically erases the U.S. bill.
Two things this page does not cover: how the UK system works step by step, and how to file both returns. For those, see how the UK tax system works for Americans, as well as our guide to U.S. expat taxes in the UK. This comparison is part of our full guide to living in the UK as an American.
At a Glance: How UK and U.S. Taxes Compare
| Tax factor | UK | U.S. |
|---|---|---|
| Tax basis | Residency | Citizenship (worldwide) |
| Tax year | April 6 to April 5 | January 1 to December 31 |
| Top income tax rate | 45% over £125,140 | 37% federal, plus state up to 13.3% |
| Tax-free allowance | £12,570 personal allowance | $15,750 single / $31,500 married (2025) |
| Social taxes | National Insurance | Social Security + Medicare |
| Consumption tax | 20% VAT, included in price | 0 to 10%+ sales tax, added at checkout |
| Capital gains | 18% or 24% | 0 to 20% long-term |
| Corporate tax | 25% over £250,000 | 21% federal flat |
Income Tax: The UK Taxes Earnings More Heavily
At most income levels, the UK takes a bigger share of your salary than the U.S. does. The UK’s 40% higher-rate band begins at £50,271, while a U.S. earner at the equivalent income level is still in the 22%-24% federal tax bracket. Only very high earners see the gap narrow, with the UK at 45% and the U.S. at 37% plus state tax.
| Income level | UK marginal rate | U.S. federal marginal rate |
|---|---|---|
| Around £30,000 / $38,000 | 20% | 12% |
| Around £60,000 / $76,000 | 40% | 22% |
| Around £150,000 / $190,000 | 45% | 24% to 32% |
The UK also has its own mechanics that sit outside the comparison, including the residency test that determines whether you are taxed at all, the PAYE payroll system, separate Scottish rates, and the taper that removes your personal allowance above £100,000. Those are covered in the article on how the UK tax system works for Americans.
Social Taxes: National Insurance vs. Social Security and Medicare
Both countries tax wages to fund pensions and health or social programs, and the headline employee rates are broadly similar, but the U.S. splits its charge into two parts and caps the larger of the two.
| Who pays | UK National Insurance | U.S. Social Security + Medicare |
|---|---|---|
| Employees | 8% on £12,570 to £50,270, then 2% | 6.2% up to $176,100, plus 1.45% Medicare |
| Self-employed | 6% Class 4, then 2% | 15.3% total, half deductible |
You do not pay into both systems on the same earnings. The U.S.-UK Totalization Agreement assigns you to one country’s system, normally the one where you work, so an American employed in the UK pays National Insurance and not U.S. Social Security.
Consumption Tax: 20% VAT vs. U.S. Sales Tax
The UK charges far more at the till, but you rarely notice it because it is already in the price. VAT is a flat 20% built into what you pay, with reduced or zero rates on essentials like most food and children’s clothing. U.S. sales tax is added at checkout and set by state, so it can range from 0% to more than 10%.
| Factor | UK VAT | U.S. sales tax |
|---|---|---|
| Standard rate | 20% | 0 to 10%+ |
| Shown in the price? | Yes | No, added at checkout |
| Set by | National government | State and local governments |
Capital Gains: Higher UK Rates, Smaller Exemption
The UK taxes investment gains at higher rates than U.S. long-term rates and gives a much smaller tax-free allowance, though it does not distinguish between short and long holdings the way the U.S. does.
| Factor | UK | U.S. |
|---|---|---|
| Rates | 18% or 24% | 0, 15, or 20% long-term; up to 37% short-term |
| Annual exemption | £3,000 | None, but $250k / $500k on a main home |
| Holding period matters? | No | Yes, over one year for the lower rates |
Because UK capital gains rates usually exceed U.S. long-term rates, the Foreign Tax Credit generally covers the U.S. tax on the same gain. One well-known mismatch is the UK ISA, which is tax-free in the UK but fully taxable to the IRS.
Corporate Tax: 25% in the UK vs. 21% in the U.S.
For companies, the two headline rates are close: the UK charges 25% on profits above £250,000 and 19% on profits up to £50,000, while the U.S. applies a flat 21% federal rate plus state tax. The bigger difference for Americans is not the rate but the additional U.S. rules that apply when a U.S. person owns a foreign company, including NCTI (formerly GILTI) and Form 5471 reporting.
Which System Costs More Overall?
For most working Americans, the UK is the higher-tax country. It taxes income and gains at higher rates, adds 20% VAT to nearly everything, and gives smaller allowances. The U.S. offsets some of that with state-by-state variation and lower headline investment rates, but a typical salaried expat pays more total tax living in the UK than they would on the same income in the U.S. The upside is that this higher UK tax is exactly what wipes out the U.S. bill through the Foreign Tax Credit.
What the Comparison Means for Your U.S. Tax Bill
Because the UK usually taxes more, the practical outcome for most Americans is simple: you pay UK tax, then claim it as a credit and owe the IRS little or nothing. The Foreign Tax Credit gives a dollar-for-dollar credit for UK tax paid, and because UK tax is higher, it typically covers your entire U.S. liability, often leaving credits to carry forward. The Foreign Earned Income Exclusion is the alternative, but in a high-tax country like the UK, the credit is usually the better choice.
The step-by-step for filing both returns, which forms to use, which order to file in, and how the U.S.-UK tax treaty fits in is in our guide to U.S. expat taxes in the UK.
Frequently Asked Questions
For most people, taxes are higher in the UK. The UK taxes income and capital gains at higher rates than U.S. federal rates at comparable income levels, and it adds 20% VAT to most purchases. U.S. total tax can rise with state taxes, but a typical salaried worker pays more overall in the UK.
They can. The UK taxes residents on their income, and the U.S. taxes citizens on worldwide income, regardless of where they live, so an American in the UK is subject to both. The Foreign Tax Credit and the tax treaty exist to stop the same income from being taxed twice.
The UK’s top income tax rate is 45% on income over £125,140. The U.S. top federal rate is 37%, though state income taxes of up to 13.3% can push the combined U.S. rate higher in states like California.
The UK tax year runs from April 6 to April 5 for historical reasons, while the U.S. uses the calendar year. The mismatch means income earned in one U.S. tax year can span two UK tax years, which is one reason coordinating the two returns requires care.
Often, yes. Because UK tax usually exceeds what you would owe the U.S. on the same income, the Foreign Tax Credit typically reduces your U.S. bill to zero. You still have to file a U.S. return and report the income, even when no tax is due.
How Greenback Can Help
Comparing the two systems is one thing; filing across both is another, with different tax years, deadlines, and rules pulling in opposite directions. We prepare your UK and U.S. returns together, so the numbers line up and you claim every credit available under the comparison.
If you would like both your UK and U.S. taxes handled by one team, our UK tax services pair a UK Chartered Accountant with a U.S. accountant on a single account. Learn more about how we help Americans living in the UK.
Lower Your Combined U.S. and UK Taxes
This article is for general informational purposes only and does not constitute tax advice. Tax laws in both countries change frequently, and individual circumstances vary. Always consult a qualified tax professional about your specific situation.
