US Expats in the UK: Complete Financial Planning Guide (2026)

The United Kingdom is home to more than 250,000 US citizens — and it's arguably the most financially complex expat destination in the world. The UK has high income tax rates, a rich but PFIC-contaminated savings ecosystem, and a pension system that interacts badly with US law. The UK-US income tax treaty is extensive but provides far less relief for US citizens than most people expect. Getting this wrong — holding Irish UCITS funds in an ISA, contributing to a SIPP without understanding §402(b), or choosing FEIE when FTC would save you $15,000 a year — adds up quickly.

1. The Core Tax Decision: Foreign Tax Credit Almost Always Wins in the UK

The two primary mechanisms US citizens abroad use to avoid double taxation are:

• Foreign Earned Income Exclusion (FEIE, Form 2555) — excludes up to $132,900 of foreign earned income from US gross income in 2026.¹
• Foreign Tax Credit (FTC, Form 1116) — applies taxes paid to the UK directly against your US tax liability, dollar for dollar.²

For US citizens working in the UK in 2026, the FTC is almost always superior. Here's why:

UK Tax Rates for 2026/2027

For the UK tax year 6 April 2026 – 5 April 2027:³

A US citizen earning £80,000 in London (roughly $100,000 at mid-2026 rates) pays approximately £22,000 in UK income tax — an effective rate near 27%. US tax on $100,000 of ordinary income for a single filer is approximately $17,000 before credits. The FTC of $22,000 fully offsets the $17,000 US liability, leaving zero US tax on that income, with $5,000 of excess credits available to carry forward 10 years.

By contrast, FEIE would exclude the first $132,900 — but you'd still owe UK taxes in full (the exclusion doesn't reduce UK liability), you'd lose IRA contribution eligibility for excluded income, self-employment tax applies in full to the excluded income under §1402(a)(8), and you'd be locked into the FEIE election for five years after revocation. Use our FEIE vs FTC calculator to model your specific situation.

The main case where FEIE has any advantage in the UK: income below the higher-rate threshold (under ~£50,270) where UK taxes paid may fall below US liability. Even then, the loss of IRA eligibility and the SE tax trap make FEIE a poor choice for most wage earners. If you're self-employed in the UK, the math is particularly lopsided toward FTC.

2. UK Pensions and US Tax Law: SIPP, Workplace Schemes, ISA

The SIPP and §402(b)

A Self-Invested Personal Pension (SIPP) is the UK's equivalent of a self-directed retirement account. For US citizens, the US tax treatment depends critically on whether contributions are personal or employer-funded:

• Employer contributions: Under IRC §402(b), employer contributions to a non-US pension plan are taxable to the US employee when they vest — not when distributed. This differs from a 401(k), where employer contributions aren't taxed until withdrawal. If your employer contributes to a group personal pension or SIPP, you should be tracking and reporting those contributions on your US return each year.⁴
• Personal contributions: Not deductible on your US return (unlike an IRA), because UK pension tax relief is at-source, not via a US deduction.
• Growth inside the SIPP: Under Article 18(1) of the UK-US income tax treaty, income earned within the pension plan is generally deferred for US tax purposes until distribution — the treaty exception survives the saving clause for pensions.
• The UK's 25% tax-free lump sum: Under US law, this is taxable. The UK allows pension holders to take 25% of their fund tax-free at retirement; the US sees this as an ordinary distribution. Treaty coordination analysis is required — don't assume it transfers across both tax systems.

Reporting: your SIPP must be disclosed on FBAR (FinCEN 114) if the total value of all foreign accounts exceeds $10,000 at any point during the year. It also goes on Form 8938 above the applicable FATCA threshold. Some SIPP structures may additionally require Form 3520 if the IRS classifies the arrangement as a foreign grantor trust.

UK Workplace Pensions (Auto-Enrollment)

Since 2012, UK employers must auto-enroll eligible workers in a workplace pension. Both you and your employer contribute. For US citizens, the same §402(b) analysis applies to employer contributions: they're taxable to you as US income when vested. The good news: if you're using the FTC and your UK tax rate is high enough, you may already have excess credits that can offset the resulting US liability. But this needs to be planned, not discovered at filing time.

UK ISA: Almost Always a PFIC Trap

The UK Individual Savings Account (ISA) is a tax-free wrapper — no UK income or capital gains tax on investments inside. For UK taxpayers, it's an excellent tool. For US citizens, it's a minefield:

• Cash ISA: Holds only cash. No PFIC issue, but also no growth benefit for a US citizen (interest is taxed in the US regardless of the ISA wrapper).
• Stocks and Shares ISA: Holds UK-domiciled or Irish-domiciled unit trusts, OEICs, or similar funds. These are almost universally Passive Foreign Investment Companies (PFICs) under IRC §1297. Holding PFICs without a QEF or mark-to-market election subjects gains to the §1291 excess distribution regime — taxed at the highest ordinary income rate plus compound interest charges stretching back to when the investment began appreciating.

US citizens generally cannot buy US-domiciled ETFs (like Vanguard or iShares US funds) in a UK ISA due to PRIIPs/UCITS regulations restricting foreign retail products in UK accounts. The practical result: a Stocks and Shares ISA is not viable for most US citizens. Use our PFIC tax impact calculator to see how badly the default regime compounds over time.

The alternative: hold US-domiciled ETFs in a taxable brokerage account (FBAR-reported), or in your US 401(k)/IRA if you have one. The tax efficiency you lose by forgoing the ISA wrapper is far less than the penalty from accidental PFIC exposure.

3. National Insurance and US Social Security

The US and UK have a Totalization Agreement (in force since 1984) that addresses dual Social Security obligations:⁵

• While working in the UK: You generally pay only into UK National Insurance (NI), not US Social Security, for the duration of your UK employment. An employer Certificate of Coverage from the SSA can formalize this.
• Benefit eligibility: If you haven't accumulated enough qualifying quarters in either country for full benefits, the totalization agreement allows NI contribution periods to be combined with US Social Security quarters to determine eligibility. The actual benefit is proportional to each country's credited contributions.
• What this doesn't cover: The totalization agreement is entirely separate from the income tax treaty. It covers Social Security and NI only — not income taxes, capital gains, or any other tax.

One important note for long-term UK expats: the Social Security Fairness Act (January 2025) repealed the Windfall Elimination Provision (WEP) and Government Pension Offset (GPO) that previously reduced Social Security benefits for people who also received a pension from non-covered employment. Those reductions no longer apply.

4. FBAR and FATCA for UK-Based Accounts

Standard FBAR and FATCA reporting obligations apply in full for UK accounts. Every UK bank account, SIPP, ISA, premium bond account, and employer pension must be evaluated:

• FBAR (FinCEN 114): required if aggregate foreign account balances exceed $10,000 at any point during the year. Barclays, HSBC, Lloyds, NatWest, Monzo, Starling — all reportable.
• Form 8938: required if foreign assets exceed $200,000 single / $400,000 MFJ on the last day of the tax year (or $300K / $600K at any point during the year) — for those living abroad.

UK banks are FATCA-compliant and report US-accountholder information to HMRC which shares it with the IRS. Do not assume FATCA compliance by the bank means you don't have to file — you still file personally.

5. The State Tax Problem: You're Probably Still a California or New York Resident

A major trap for US expats in the UK: moving to London doesn't automatically end your state tax liability. If you lived in California or New York before the move, you may still owe state income tax on your worldwide income — and unlike the federal return, state taxes don't recognize FEIE and rarely provide full foreign tax credits.

California, in particular, does not recognize the federal Foreign Earned Income Exclusion. Income you exclude on Form 2555 may still be fully taxable in California if you haven't formally changed your California domicile. The FTC at the federal level does not flow through to California's return in the same way. See our state residency planning guide for what it takes to properly sever California or New York domicile.

6. What to Do Before Moving to the UK

The most expensive mistakes are made in the months before departure. Before you move:

1. Make the FEIE vs FTC decision. Modeling both scenarios takes about 30 minutes with a specialist; getting it wrong costs years of excess tax. If you've already filed with FEIE and FTC would be better, you can switch — but you trigger the 5-year revocation lock-in.
2. Assess your brokerage accounts. If you own foreign mutual funds (or US-listed ETFs that hold foreign securities above the PFIC income threshold), evaluate before moving — while you're still a US resident, you have more flexibility to reposition. Post-departure, selling may trigger additional US and UK tax events to coordinate.
3. Sever your high-tax-state domicile properly. Change driver's license, voter registration, bank accounts, and professional relationships. Cancel your lease or rent out your property rather than keeping it available as a pied-à-terre. Document the move date.
4. Understand your employer's pension contribution plan. If your UK employer will contribute to a SIPP or workplace pension, get clarity on vesting schedules and amounts — these are taxable US income in the year they vest, and should be planned for.
5. Confirm your IRA strategy. If you use FEIE, you lose IRA contribution eligibility for excluded income. If you use FTC (recommended), you retain it as long as you have US earned income after the credit offset. A Roth conversion may be worth doing before departure while you're still in a US tax environment.

What a UK-Specialist Expat Advisor Handles

Most US financial advisors cannot or will not take clients who live outside the US. Most UK-based advisors can't handle US tax obligations. The intersection — a US-licensed, fee-only advisor who specializes in US expats in the UK — is rare. What they do:

• Model FEIE vs FTC for your specific income, filing status, and UK tax position
• Review your SIPP, ISA, and workplace pension for §402(b) exposure and PFIC risk
• Coordinate UK and US tax returns to avoid double taxation and capture treaty benefits
• Advise on portfolio construction: what to hold, where, and in what account type
• Handle FBAR/FATCA compliance and advise on PFIC elections (QEF or MTM) if you've inherited foreign funds
• Plan the move: severance of state domicile, account restructuring, timing of Roth conversions
• Non-US spouse planning: QDOT trust if estate assets approach the $15M exemption, gift limit ($194,000/yr for non-citizen spouses in 2026), FBAR signature authority

1. IRS Publication 54, Tax Guide for U.S. Citizens and Resident Aliens Abroad — Foreign Earned Income Exclusion. 2026 FEIE limit $132,900 per Rev. Proc. 2025-28. irs.gov/publications/p54
2. IRC §901–§905; IRS Form 1116 Instructions (2026). Foreign Tax Credit framework. irs.gov/forms-pubs/about-form-1116
3. HMRC: Income Tax rates and Personal Allowances for the 2026 to 2027 tax year — Personal Allowance £12,570, basic rate 20% (up to £50,270), higher rate 40% (up to £125,140), additional rate 45%. gov.uk/income-tax-rates
4. IRC §402(b): taxation of employer contributions to non-exempt trusts. IRS Revenue Ruling 2014-1 and IRS Notice 97-34 cover foreign pension plans. See also IRS Publication 901, U.S. Tax Treaties. irs.gov/publications/p901
5. SSA: US-UK Totalization Agreement (entered into force January 1, 1985). Prevents dual Social Security contributions; allows combined US/UK credits for benefit eligibility. ssa.gov/international/Agreement_Pamphlets/uk.html

Tax values verified as of April 2026. UK rates are for the 2026/2027 tax year (6 April 2026 – 5 April 2027). US values are for US tax year 2026.