U.S. Taxes for American Expats Living in the UK

Who Must File U.S. Taxes from the UK

The United States is one of only two countries that tax residents by citizenship rather than residence. That single fact reshapes the financial life of every American who moves to Britain: once a U.S. citizen or green card holder, your worldwide income remains reportable to the IRS even after you have established a full life under HMRC.

A filing requirement is triggered when your worldwide gross income exceeds the IRS threshold for your filing status. For the 2025 tax year — the return filed in 2026 — those thresholds are:

Green card holders are treated identically to citizens for filing purposes. The rule also applies regardless of how long you have lived in the UK — there is no years-of-absence exemption.

Why Most American Expats in the UK Don't Pay Tax Twice

British income tax rates are often higher than U.S. rates at equivalent income levels, particularly in the basic and higher rate bands. This works in favour of American residents in the UK: because HMRC usually takes a larger share first, the IRS frequently finds little or nothing left to collect once reliefs are applied.

Two mechanisms do most of the protective work. The Foreign Earned Income Exclusion (FEIE) allows a portion of foreign earned income to be excluded from U.S. taxable income entirely — the exclusion amount for the 2025 tax year is $130,000, rising to $132,900 for 2026. The Foreign Tax Credit (FTC) instead offsets U.S. tax dollar-for-dollar with income tax already paid to HMRC.

For most salary earners in the UK, one or a combination of these reliefs eliminates any U.S. tax liability. The return still needs to be filed — it is the mechanism through which the reliefs are formally claimed.

FEIE vs Foreign Tax Credit — Choosing the Right Approach

Most UK-based Americans choose between these two routes, and the right choice depends on your income mix, salary level, and longer-term plans.

Foreign Earned Income Exclusion (Form 2555)

The FEIE excludes qualifying earned income (salary, self-employment income, bonuses) from U.S. taxable income up to $130,000 for 2025. To claim it, you must meet either the bona fide residence test (established as a genuine resident of the UK for a full tax year) or the physical presence test (present outside the U.S. for at least 330 full days in any 12-month period). Most Americans settled in the UK qualify through bona fide residence.

The FEIE is simpler to apply for straightforward employment situations but does not reduce self-employment tax (Social Security and Medicare contributions continue to apply to excluded income, though the UK–U.S. Totalization Agreement typically prevents dual Social Security contributions for employees).

Foreign Tax Credit (Form 1116)

The FTC credits income tax paid to HMRC against U.S. tax liability. For most UK-based employees, UK tax paid at the basic or higher rate is sufficient to eliminate any U.S. bill. Any unused credits can be carried back one year or forward ten, which can be useful in years with variable income.

The FTC is generally preferable for higher earners (income well above the FEIE limit), for those who plan to return to the U.S. and want to preserve pension treaty benefits, and for taxpayers with significant unearned income such as dividends and rental income, which the FEIE does not cover. Unearned income cannot be excluded under the FEIE, but it can attract FTC credits.

How UK Employment Income Appears to the IRS

British payslips and the U.S. tax return speak different languages. There is no U.S. equivalent of a P60 or P45, and PAYE — which deducts income tax silently before salary reaches your account — has no direct counterpart in American tax culture. For IRS purposes, the translation works as follows:

• Your salary, bonuses, and taxable benefits must be converted from pounds to dollars. The IRS accepts either the annual average exchange rate published by the Treasury (suitable for regular salary) or the specific rate on the date of a transaction (more appropriate for one-off events such as a bonus or property sale).
• National Insurance contributions are not credited as foreign tax against your U.S. liability — only income tax qualifies for the FTC. If you pay both UK income tax and National Insurance on the same earnings, only the income tax portion offsets U.S. liability.
• Employer benefits — company cars, private medical insurance, cycle-to-work schemes — may have UK P11D values that require separate treatment in the U.S. return.

Keeping a simple annual record — payslips saved, P60 filed, exchange rate noted — turns what can feel like a translation problem into a routine administrative task.

UK Pensions, ISAs, and Savings Accounts

This is where the two systems diverge most sharply, and where taking professional advice is most likely to be worthwhile.

Workplace pensions and SIPPs

UK workplace pensions — auto-enrolment schemes, defined benefit schemes, and SIPPs — are treated favourably under the UK–U.S. tax treaty. The treaty generally allows contributions to receive tax deferral similar to a 401(k): employee and employer contributions are not immediately taxable in the U.S., and growth is tax-deferred. You should not need to report pension growth each year as current income if the treaty position is properly claimed on Form 8833.

However, workplace pensions may require disclosure on Form 8938 (FATCA) if the total value of your foreign financial assets exceeds the relevant threshold. At retirement, U.S. tax treatment of withdrawals depends on the treaty and the type of pension — defined contribution and defined benefit pensions are treated differently.

ISAs

Individual Savings Accounts enjoy a starker contrast. The "tax-free" description is accurate under UK law, but the IRS does not recognise the ISA wrapper. Interest, dividends, and gains inside an ISA remain reportable for U.S. purposes, exactly as if the ISA did not exist. Cash ISA interest, stocks and shares ISA dividends, and capital gains from an ISA are all potentially taxable in the U.S. return.

Beyond the income reporting issue, stocks and shares ISAs that hold funds (rather than individual shares) may trigger Passive Foreign Investment Company (PFIC) rules under the IRS. PFIC reporting (Form 8621) is complex and potentially costly. Many U.S.-aware financial advisers recommend that American expats avoid holding pooled investment funds in ISAs for this reason, or restructure holdings to consist of individual shares and ETFs listed on recognised U.S. exchanges.

Selling UK Property as a U.S. Citizen

Selling a British home can produce a tax event in the U.S. even when HMRC sees none.

Under UK law, gains on a primary residence are typically exempt from capital gains tax under Principal Private Residence (PPR) relief. The IRS applies its own rules: the U.S. principal residence exclusion allows up to $250,000 of gain ($500,000 for married couples) to be excluded from U.S. tax, provided you have owned and lived in the property as your main home for at least two of the five years before sale.

Two complications frequently arise. First, the dollar–sterling exchange rate: the gain for U.S. purposes is calculated in dollars, using the dollar value at purchase and at sale. If sterling has strengthened since you bought, your dollar gain may be larger than your pound gain — and vice versa. Second, if the property was not your primary residence throughout your ownership (for example, it was rented before you moved in), the portion of the gain attributable to that period may not qualify for the U.S. exclusion. Plan sales with awareness of both systems, ideally before exchanging contracts.

FBAR and FATCA — Reporting Your UK Bank Accounts

Two separate reporting obligations apply to most Americans in the UK, neither of which is a tax but both of which carry significant penalties for non-compliance.

FBAR — FinCEN Form 114

If the aggregate value of all your foreign financial accounts exceeded $10,000 at any point during the calendar year, you must file an FBAR. The threshold is combined across all accounts — a current account at £6,000 and a savings account at £5,000 on the same day would trigger a requirement even if neither account alone crosses the equivalent of $10,000.

The FBAR is filed electronically through FinCEN's BSA E-Filing system — it is not part of your IRS tax return. The deadline is 15 April with an automatic extension to 15 October. Accounts held jointly with a British spouse, and accounts where you have signatory authority (such as an employer account you sign for), count toward the threshold.

FATCA — Form 8938

Form 8938 is filed with your IRS tax return and covers a broader range of foreign financial assets including investments, pension interests, and foreign company ownership. For a single taxpayer living abroad, the threshold is $200,000 at year-end or $300,000 at any point during the year. For married couples filing jointly, these thresholds double.

Filing the FBAR does not satisfy the Form 8938 requirement, and vice versa. Both must be filed if you meet the respective thresholds.

State Taxes After Moving to the UK

Federal rules are only part of the picture. Several U.S. states — most notably California, New York, and Virginia — have a reputation for asserting continuing tax residency over former residents who moved abroad without formally severing ties.

What counts as a continuing tie varies by state but can include: owning property in the state, maintaining a driving licence, keeping voter registration, holding professional licences, or returning to the state frequently. None of these alone is conclusive, but together they can support a state's claim that you remained domiciled there.

If you moved from one of the more aggressive states, it is worth taking specific advice about that state's residency rules and, if appropriate, formally establishing domicile in a state with no income tax before departing the U.S. — or documenting the break clearly before it becomes a question years later.

Contractors, Freelancers, and Self-Employment Income

Self-employment in the UK adds complexity to the U.S. return on several fronts. UK income from self-employment must be reported on a Schedule C. Self-employment tax (12.4% Social Security and 2.9% Medicare) applies to net earnings above $400 regardless of where the work is performed — the FEIE excludes income from U.S. income tax but not from self-employment tax.

The UK–U.S. Totalization Agreement prevents dual Social Security contributions for employees, but its application to the self-employed is more nuanced. If you are self-employed and paying UK National Insurance, you should take specific advice on whether U.S. self-employment tax also applies to your situation.

Americans who issue or receive U.S. 1099 forms — for example, those invoicing U.S. clients — may also need to file information returns. Platforms such as Tax1099, an IRS-authorised e-filing service, can help contractors manage the information-return side of cross-border self-employment from abroad.

Deadlines and Extensions for Americans Abroad

Americans living outside the United States receive an automatic two-month extension beyond the standard 15 April deadline. In practice this means:

• 15 April — standard deadline (and payment deadline if tax is due)
• 15 June — automatic extended deadline for Americans abroad (no request needed)
• 15 October — further extension available on request (Form 4868), but this extends the filing deadline only — any tax due should still be paid by 15 June to avoid interest

The extended timeline is practically useful: it allows the UK tax year (which ends in April) to settle before you prepare the U.S. return, so you are not estimating figures that will later be confirmed by your P60 or interest statements.

Behind on Filing? The Streamlined Foreign Offshore Procedure

Many Americans in the UK discover the filing requirement years after moving — sometimes on the eve of a mortgage application, a return to the U.S., or a major financial event. The IRS distinguishes between deliberate evasion and people who have been paying UK taxes and simply were unaware of or confused about their U.S. obligations.

For those who qualify, the Streamlined Foreign Offshore Procedure (SFOP) provides a penalty-free path to compliance. The programme requires:

• Filing the three most recent years of overdue U.S. tax returns
• Filing six years of overdue FBARs through FinCEN
• Paying any tax and interest owed (penalties are waived)
• Signing Form 14653, certifying that the failure to file was non-willful

Each return should be marked "Streamlined Foreign Offshore" in red and submitted to the designated IRS address in Austin, Texas. The procedure requires you to demonstrate that non-compliance resulted from negligence, inadvertence, or honest misunderstanding — not deliberate tax avoidance. Specialist expat tax firms can help structure the certification and returns correctly.

The UK–U.S. Tax Treaty in Plain Terms

The convention between the United Kingdom and the United States — in force since 1980 and updated most recently in 2003 — is the framework that prevents most practical double taxation. Its key effects for everyday expat life include:

• Pensions: UK workplace pensions are treated with similar deference to U.S. retirement accounts, protecting contributions and growth from immediate U.S. taxation (see the pensions section above and Form 8833 for claiming treaty benefits).
• Dividends and interest: Reduced withholding rates apply to cross-border income flows, which matters if you have U.S. investment accounts while living in the UK.
• Government employment: Salaries paid by the UK government to non-UK citizens may be taxable only in the U.S.; salaries paid by the U.S. government are typically only taxable in the U.S. This creates specific rules for civil servants and military personnel.
• Tie-breaker rules: Where both countries could claim you as a tax resident simultaneously, the treaty provides a hierarchy of tests (permanent home, habitual abode, centre of vital interests, nationality) to determine which country has primary residence rights.

Treaty claims are made on your U.S. return using Form 8833. Not claiming treaty positions you are entitled to can result in paying more than you owe.

When to Get Professional Help

Many Americans in the UK manage their returns independently after the first year, once the pattern becomes familiar. Others choose professional assistance from the outset — particularly in years involving a property sale, a business change, pension decisions, or catching up on missed filings.

The ecosystem of expat-focused tax services has matured considerably. Firms such as Greenback Expat Tax Services and MyExpatTaxes specialise in the cross-border returns of Americans abroad. For contractors and freelancers who need to manage information returns, Tax1099 provides an IRS-authorised platform for e-filing 1099s, W-2s, and related forms from outside the U.S.

The decision is as much about temperament as need. A straightforward employment situation with no UK investments and no self-employment can often be handled independently with care. A more complex picture — PFIC-exposed ISA holdings, a UK pension with treaty claims, self-employment across borders, or years of unfiled returns — generally warrants professional input.

FAQ: U.S. Taxes in the UK