UK vs. U.S. Taxes for Expats: Rates, Key Differences, and How to Avoid Double Tax
The UK and the U.S. both tax income, capital gains, and social contributions, but the two systems work in fundamentally different ways. The UK taxes based on residency (where you live), while the U.S. taxes based on citizenship (who you are). For Americans living in the UK or British nationals living in the U.S., this means you could owe taxes to both countries on the same income. The good news: the UK-US tax treaty, the Foreign Tax Credit, and the Foreign Earned Income Exclusion work together to prevent double taxation, and most dual citizens owe $0 to the IRS after applying these protections.
According to the IRS, U.S. citizens must file a federal return on worldwide income regardless of where they live. Because UK tax rates are generally higher than U.S. rates across most income levels, the Foreign Tax Credit typically eliminates the entire U.S. tax bill for Americans in the UK. Here’s a side-by-side comparison of every major tax category and how dual filers can avoid paying twice.
Not Sure How UK and U.S. Taxes Work Together?
At a Glance: UK vs. U.S. Tax Systems
| Tax Factor | UK Tax System | U.S. Tax System |
|---|---|---|
| Tax basis | Residency-based: taxes UK residents on worldwide income | Citizenship-based: taxes U.S. citizens on worldwide income regardless of where they live |
| Tax year | April 6 to April 5 | January 1 to December 31 |
| Top income tax rate | 45% on income over £125,140 | 37% federal, plus state taxes up to 13.3% |
| Standard deduction/allowance | £12,570 Personal Allowance (2025/26) | $15,750 single / $31,500 MFJ (2025) |
| Social taxes | National Insurance Contributions (NICs) | Social Security + Medicare (FICA) |
| Sales/consumption tax | 20% VAT included in prices | 0-10% state/local sales tax added at checkout |
| Corporate tax | 25% on profits over £250,000 | 21% federal, plus state taxes up to 12% |
| Capital gains tax | 18-24% with £3,000 annual exemption | 0-20% long-term; up to 37% short-term |
| Filing deadline | January 31 (Self Assessment) | April 15 (June 15 auto-extension for expats) |
From April 2025, the UK’s new Foreign Income and Gains (FIG) regime allows eligible new residents to shield foreign income from UK tax for four years, modifying the practical impact of residency-based taxation during that period. In exchange, you give up the Personal Allowance (£12,570) and Capital Gains Tax annual exemption (£3,000).
How Does Income Tax Compare Between the UK and the U.S.?
UK Income Tax
The UK determines tax obligations based on residency, assessed under the Statutory Residence Test (SRT). If you spend 183 or more days in the UK during a tax year, you are generally a UK tax resident. Fewer than 183 days trigger the “sufficient ties” test, which considers factors such as your home, family, work, and time spent in the UK.
UK Income Tax Rates for 2025/26 (England, Wales, and Northern Ireland):
| Band | Taxable Income | Rate |
|---|---|---|
| Personal Allowance | Up to £12,570 | 0% |
| Basic rate | £12,571 to £50,270 | 20% |
| Higher rate | £50,271 to £125,140 | 40% |
| Additional rate | Over £125,140 | 45% |
Most employees are taxed through PAYE (Pay As You Earn), where tax is deducted automatically from each paycheck. Self-employed individuals, those earning above £150,000, or anyone with rental or investment income, typically file a Self Assessment tax return by January 31. Learn more in our UK Self Assessment guide.
Scotland has different rates. Scottish taxpayers face a six-band system with rates ranging from 19% (Starter) to 48% (Top rate) for 2025/26. If you live in Scotland, check the Scottish income tax bands separately.
The £100,000 tax trap: Your Personal Allowance is reduced by £1 for every £2 earned above £100,000, creating an effective marginal rate of 60% between £100,000 and £125,140, which is higher than the 45% additional rate.
U.S. Federal Income Tax
The U.S. taxes based on citizenship, not residence. All U.S. citizens and green card holders must file annually and report worldwide income, no matter where they live.
U.S. Federal Tax Brackets for 2025 (Single Filers):
| Taxable Income | Rate |
|---|---|
| $0 to $11,925 | 10% |
| $11,926 to $48,475 | 12% |
| $48,476 to $103,350 | 22% |
| $103,351 to $197,300 | 24% |
| $197,301 to $250,525 | 32% |
| $250,526 to $626,350 | 35% |
| Over $626,350 | 37% |
The One Big Beautiful Bill Act (OBBB), signed on July 4, 2025, made these rates permanent (they had previously been set to expire at the end of 2025) and increased the standard deduction to $15,750 for single filers and $31,500 for married filing jointly. The OBBB also created a new $6,000 senior deduction for taxpayers 65 and older (2025-2028), which phases out above $75,000 MAGI ($150,000 MFJ).
U.S. tax returns are due April 15, but Americans living abroad receive an automatic extension to June 15. You can request a further extension to October 15 by filing Form 4868. Any taxes owed are still due by April 15, regardless of extensions.
U.S. state income taxes add another layer of complexity. States like California (up to 13.3%), New York, and New Jersey impose their own income taxes, and some states continue taxing former residents even after they move abroad. Learn more about state tax obligations for expats.
How Do Social Taxes Compare? NICs vs. FICA
Both countries tax wages to fund social benefits, but the UK’s National Insurance Contributions (NICs) and the U.S. Social Security/Medicare (FICA) differ in scope and cost.
UK National Insurance Contributions (2025/26)
| Who Pays | Rate | Threshold |
|---|---|---|
| Employees | 8% | On earnings £12,570 to £50,270; 2% above £50,270 |
| Employers | 15% | On earnings above £5,000 per worker |
| Self-employed | 6% Class 4 | On profits £12,570 to £50,270; 2% above; plus £3.45/week Class 2 if profits exceed £6,725 |
NICs fund the National Health Service (NHS), state pensions, and unemployment benefits. Unlike U.S. Social Security, there is no annual earnings cap for the 2% higher rate.
U.S. Social Security and Medicare Taxes (2025)
| Who Pays | Social Security | Medicare | Total |
|---|---|---|---|
| Employees | 6.2% (up to $176,100) | 1.45% (no cap) | 7.65% |
| Employers | 6.2% (up to $176,100) | 1.45% (no cap) | 7.65% |
| Self-employed | 12.4% (up to $176,100) | 2.9% (no cap) | 15.3% |
| High earners | Same as above | Additional 0.9% on income over $200,000 | Varies |
The Social Security wage base for 2025 is $176,100. Self-employed individuals pay both the employee and employer portions (15.3% total), though they can deduct half of this on Schedule 1.
The U.S.-UK Totalization Agreement
The U.S.-UK Totalization Agreement (1984 treaty) prevents you from paying social taxes to both countries on the same earnings. Generally, you pay into the country’s social security system. If your U.S. employer sends you to the UK on a temporary assignment (up to 5 years), you can continue paying only into U.S. Social Security. The agreement also allows you to combine work credits from both countries to qualify for retirement benefits in either system.
How Does VAT Compare to U.S. Sales Tax?
UK Value Added Tax (VAT)
VAT is built into the price of nearly everything you buy in the UK. The standard rate is 20%. Some items qualify for reduced rates: home energy and children’s car seats are charged at 5%, while most food, children’s clothing, and books are charged at 0% VAT. Businesses with an annual turnover above £90,000 must register for VAT.
The key difference from a consumer perspective: the price you see on the shelf is the price you pay. VAT is already included.
U.S. Sales Tax
The U.S. has no national sales tax. Instead, individual states (and sometimes cities and counties) set their own rates, which range from 0% in states like Delaware, Montana, and Oregon to over 10% in parts of Tennessee, Louisiana, and Arkansas. The price on the shelf does NOT include sales tax. It’s added at checkout, which is a common surprise for UK residents visiting the U.S.
| Factor | UK VAT | U.S. Sales Tax |
|---|---|---|
| Rate | 20% standard (5% reduced, 0% exempt items) | 0-10%+ (varies by state and locality) |
| Included in price? | Yes | No (added at checkout) |
| Who sets the rate? | National government | State and local governments |
| Applies to services? | Yes (most services) | Varies by state |
How Does Capital Gains Tax Compare?
Both countries tax profits from the sale of assets like stocks, property, and crypto, but the rates and exemptions differ significantly.
| CGT Factor | UK (2025/26) | U.S. (2025) |
|---|---|---|
| Rates | 18% (basic rate taxpayers) / 24% (higher/additional rate) | 0%, 15%, or 20% long-term; up to 37% short-term |
| Annual exemption | £3,000 tax-free allowance | No annual exemption (but $250K/$500K exclusion on primary home sale) |
| Short vs. long-term distinction | No (same rates regardless of holding period) | Yes (assets held over one year qualify for lower long-term rates) |
| Reporting | Via Self Assessment | Schedule D + Form 8949 |
| Residential property | 18% / 24% (no primary residence relief if it’s not your main home) | Exclusion of $250K (single) / $500K (MFJ) on primary home |
For dual filers: Capital gains are reported to both HMRC and the IRS. The Foreign Tax Credit typically eliminates the U.S. tax on gains already taxed by the UK, since UK CGT rates (18-24%) generally exceed U.S. long-term rates (0-20%).
Important for Americans in the UK: UK ISAs (Individual Savings Accounts) are tax-free in the UK, but the IRS does not recognize ISAs as tax-exempt. Interest, dividends, and capital gains within ISAs are fully taxable on your U.S. return. This is one of the most common tax traps for U.S.-UK dual citizens.
Living in the UK as a U.S. Citizen?
How Does Corporate Tax Compare?
| Factor | UK | U.S. |
|---|---|---|
| Main rate | 25% on profits over £250,000 | 21% federal (flat rate) |
| Small profits rate | 19% on profits up to £50,000 (marginal relief between £50,000 and £250,000) | No federal small business rate (same 21%) |
| State/local taxes | No additional regional corporate taxes | State corporate taxes up to 12% on top of federal |
| Filing deadline | 12 months after accounting period ends; payment due 9 months and 1 day after | April 15 (or 15th day of 4th month after fiscal year end); extensions available |
For expat business owners with entities in both countries, the interaction between UK Corporation Tax and U.S. GILTI/NCTI rules creates additional complexity. The UK’s 25% corporate rate exceeds the NCTI threshold (~14% for 2026), meaning most UK-based corporations qualify for the GILTI high-tax exception, effectively eliminating additional U.S. tax on UK business profits.
How Do I Avoid Double Taxation Between the UK and the U.S.?
Three protections work together to eliminate double taxation for most Americans in the UK:
1. Foreign Tax Credit (FTC)
The Foreign Tax Credit provides a dollar-for-dollar credit against your U.S. tax for income taxes paid to the UK. Since UK rates are generally higher than U.S. rates, the FTC typically eliminates your entire U.S. tax bill and generates excess credits you can carry forward for up to 10 years.
Example: Sarah earns $120,000 in London and pays £22,000 (~$28,000) in UK income tax. Her U.S. tax on $120,000 (after the standard deduction) would be approximately $14,000. The FTC wipes out the full $14,000, and she has $14,000 in excess credits to carry forward. Sarah owes the IRS $0.
2. Foreign Earned Income Exclusion (FEIE)
The FEIE excludes up to $130,000 (2025) of foreign earned income from U.S. taxation. While available to Americans in the UK, the FTC is usually the better strategy because UK tax rates exceed U.S. rates. Using the FEIE in a high-tax country like the UK means you can’t claim the FTC on the same income, potentially wasting valuable credits.
3. UK-US Tax Treaty
The UK-US tax treaty determines which country has primary taxing rights over specific types of income, including employment income, pensions, dividends, interest, and royalties. Key treaty provisions for expats include reduced withholding rates on cross-border investment income and coordination of pension taxation. To claim certain treaty benefits, you may need to file Form 8833.
What Reporting Requirements Apply to Both Countries?
Americans in the UK face dual reporting obligations beyond just income tax:
| Requirement | What It Covers | Threshold |
|---|---|---|
| U.S. Form 1040 | Worldwide income | Filing thresholds ($15,750 single, $31,500 MFJ for 2025) |
| UK Self Assessment | UK income (if required) | Varies (self-employed, income over £100,000, rental income, etc.) |
| FBAR (FinCEN Form 114) | Foreign financial accounts | $10,000 aggregate at any point during the year |
| FATCA (Form 8938) | Foreign financial assets | $200,000 year-end / $300,000 at any point (single expats abroad) |
| Form 3520 | Foreign gifts or trust transactions | $100,000+ from foreign individuals |
Filing order tip: Most expats file their UK Self Assessment first (deadline January 31), then use those figures for their U.S. return (deadline June 15 for expats, extendable to October 15). Filing UK first gives you the exact foreign tax paid figures needed for the Foreign Tax Credit calculation on your U.S. return.
What UK-Specific Tax Traps Catch Americans?
- ISAs are not tax-free for the IRS. UK Individual Savings Accounts are tax-sheltered in the UK, but the IRS treats ISA income (interest, dividends, capital gains) as fully taxable. Gains must be reported on your U.S. return even though you owe nothing to HMRC.
- UK pensions require U.S. reporting. Workplace pensions (including NEST and auto-enrollment schemes) must be reported on your U.S. return. Treaty provisions generally defer U.S. tax on pension contributions and growth, but distributions are taxable. Some UK pension schemes may be classified as foreign trusts, potentially triggering Form 3520 reporting.
- Making Tax Digital (MTD) is rolling out. Starting April 2026, self-employed individuals and landlords with income over £50,000 must file quarterly digital updates with HMRC using compatible software. This is in addition to your annual U.S. filing obligations.
- The FIG regime may not help most Americans. The new Foreign Income and Gains regime (from April 2025) offers four years of UK tax relief on foreign income for qualifying new UK residents. However, you lose your Personal Allowance (£12,570), and CGT annual exemption (£3,000), and you still owe U.S. tax on worldwide income regardless. For most Americans, the math doesn’t favor the FIG election.
Frequently Asked Questions
If you’re a U.S. citizen or green card holder living in the UK, yes. The U.S. taxes based on citizenship, so you must file a U.S. return on worldwide income regardless of where you live. If you’re also a UK tax resident (183+ days or sufficient ties), you’ll likely need to file a UK Self Assessment. The UK-US tax treaty and Foreign Tax Credit prevent you from paying tax twice on the same income.
File your UK Self Assessment first (deadline January 31), then use those figures for your U.S. return (deadline June 15 for expats, extendable to October 15). Filing UK first gives you the exact foreign tax paid amount needed for the Foreign Tax Credit on your U.S. return.
The Foreign Tax Credit is almost always better for Americans living in the UK. Because UK income tax rates (20-45%) generally exceed U.S. federal rates (10-37%) at comparable income levels, the FTC typically eliminates your entire U.S. tax bill and generates excess credits you can carry forward for 10 years. The FEIE would waste these valuable credits.
No. While ISAs (Individual Savings Accounts) are completely tax-free in the UK, the IRS does not recognize UK ISAs as tax-sheltered accounts. All interest, dividends, and capital gains within your ISA must be reported and are taxable on your U.S. return.
If your combined foreign financial accounts (including UK bank accounts, investment accounts, and pensions) exceed $10,000 at any point during the year, you must file an FBAR. If your foreign financial assets exceed $200,000 on December 31 (or $300,000 at any point) as a single expat abroad, you also need to file Form 8938 with your tax return.
UK workplace pensions (including auto-enrollment and NEST) must be reported on your U.S. return. The UK-US tax treaty generally allows contributions to grow tax-deferred, but distributions are taxable. Some UK pension schemes may be classified as foreign trusts by the IRS, potentially triggering Form 3520 reporting. The UK state pension is also reportable as income on your U.S. return.
No, thanks to the U.S.-UK Totalization Agreement. Generally, you pay into the social security system of the country where you work. If you’re employed in the UK, you pay only UK National Insurance. The agreement also lets you combine work credits from both countries to qualify for retirement benefits.
Making Tax Digital (MTD) for Income Tax Self-Assessment launches in April 2026 for self-employed individuals and landlords with qualifying income over £50,000. If you fall into this category, you’ll need to file quarterly digital updates with HMRC using compatible software, in addition to your annual U.S. filing obligations.
Filing taxes in both the UK and the U.S. involves coordinating two systems with different deadlines, tax years, and rules. But with the right strategy, most Americans in the UK owe the IRS nothing while remaining fully compliant with both HMRC and the IRS.
If you’re a U.S.-UK dual citizen, see our dedicated guide on managing dual filing obligations. For the full UK filing guide, see our U.S. expat taxes in the UK guide.
If you’re ready to be matched with a Greenback accountant, click the get started button below. For general questions about filing in the UK and the U.S., or about working with Greenback, contact our Customer Champions.
Lower Your Combined U.S. and UK Taxes
This article is for informational purposes only and does not constitute tax advice. Tax laws in both the UK and the U.S. change frequently, and individual circumstances vary. Always consult with a qualified tax professional regarding your specific situation.
Related Resources
- U.S. Expat Taxes in the UK: Country Guide
- U.S.-UK Dual Citizen Tax Guide
- Foreign Tax Credit: How Expats Can Reduce U.S. Taxes
- Foreign Earned Income Exclusion
- U.S. Tax Treaties
- Totalization Agreements
- FBAR Filing Requirements
- FATCA Reporting
- Dual Citizen Taxes Explained
- UK Self Assessment Guide for U.S. Expats
