The United Kingdom's departure rules are relatively straightforward compared to countries like Canada, Germany, or France — there is no UK exit tax, and the UK operates a clean 'split year treatment' that taxes you as a UK resident for the portion of the year before departure and a non-resident thereafter. However, 'no exit tax' does not mean 'no UK tax obligations after leaving.' The UK retains taxing rights on UK-source income and UK residential property gains indefinitely — obligations that catch many departed expats off guard. This guide covers the specific HMRC forms, the ISA situation, state pension planning, and the critical non-resident CGT rules that apply to former UK residents.
UK-to-USA is one of the world's most common high-skilled migration corridors. Beyond the tax rules above, these UK-US specific points matter:
P85 form: Complete HMRC Form P85 (Getting your Income Tax right if you're leaving the UK) online via Government Gateway. This tells HMRC you are leaving and triggers a tax code review. If you are employed, your employer should also update your payroll. If self-employed, notify HMRC as part of your final Self Assessment.
UK pension to USA: If you have a UK defined contribution pension pot, you cannot transfer it to a US 401(k) or IRA (QROPS rules prevent this unless the receiving scheme is HMRC-recognised). Options: leave the pension in the UK (it remains invested, accessible at UK pension age — currently 57 from 2028); transfer to a QROPS in a third country. UK drawdown from the USA: 10% UK withholding under the UK-USA tax treaty on periodic pension income; claim as Foreign Tax Credit on your US return.
UK-USA dual filing year: In your year of departure, you are filing both a UK Self Assessment (April 6 to departure date as UK resident; then non-resident for rest of year) and a US Form 1040 for the portion after you become a US tax resident. Work with a cross-border tax advisor who understands both UK SA109 and US first-year residency elections (1040-NR vs 1040 with dual-status return).
Double Taxation Agreement: The UK-USA DTA is comprehensive. UK-source income (pension, rental, dividends) can generally be claimed as a Foreign Tax Credit on your US return. The tiebreaker clause determines which country has primary residency rights if you have connections to both.
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