Moving Abroad → USA
🇺🇸Moving from UK to USA, UK Tax Framework
The UK-USA emigration corridor is the most complex bilateral in HMRC's network. Roughly 700,000 UK-born people live in the USA, the largest single emigration corridor. Complexity has three sources: the UK-USA DTA's saving clause at Article 1(4), which lets the USA tax its citizens regardless of treaty provisions; the FATCA reporting overlay, parallel to the DTA and not modifiable by it; and the recent March 2025 HMRC interpretation change on Article 17(2) pension lump sums for dual UK/US persons.
Below is the framework. Residence determination via UK SRT plus US Substantial Presence Test plus Article 4 treaty tie-breaker. DTA mechanics article-by-article. The Article 17(2) March 2025 reversal. FATCA plus Form 8938 plus FBAR overlay. UK-USA Social Security Totalization Agreement 1984. ISA position and the PFIC trap. UK IHT plus US estate tax under the 1978 Estate Tax Treaty. Most UK-side positions are unambiguous within the framework. Qualified dual-jurisdiction UK-USA practitioners exist via CIOT International and AICPA International at appropriate fees for genuinely complex cases, well below the 8k-plus cold-pitch retainer market.
Roughly 700,000 UK-born residents in the USA, the largest single UK emigration corridor. USA dominates UK emigration commercial flow, the corridor every international tax practitioner knows.
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Guidance, not advice. We explain the rules, we don't assess your situation. Always seek financial or tax advice from your accountant, or contact HMRC. Read our editorial scope →
Country overview
Residence test
US tax residence is determined by one of three tests. (1) Substantial Presence Test under IRC s.7701(b): a 3-year weighted formula equal to days in current year plus one-third of days in prior year plus one-sixth of days in the year before; 183 or more weighted days equals US tax residence. (2) Green Card holders are US tax residents by default until status is formally terminated. (3) First-year choice election under IRC s.7701(b)(4) with specific conditions. The Closer Connection Exception on Form 8840 can override the Substantial Presence Test in narrow circumstances. Where you are dual-resident under both UK and US domestic tests, the UK-USA DTA Article 4 tie-breaker applies.
Key tax structures
- Federal income tax (graduated brackets, top rate 37 percent) plus state income tax (0 percent in TX/FL/NV/WA; up to 13.3 percent in CA and 10.9 percent in NY)
- FICA: Social Security 6.2 percent plus Medicare 1.45 percent (employee plus employer match), equivalent to UK NI but with totalization overlay
- Federal estate tax exemption 13.99m USD for 2025 with a higher amount expected for 2026 under OBBBA (verify before reliance), much higher than the UK NRB plus RNRB; some states levy separate estate tax with much lower thresholds (NY 7.16m USD, MA 2m USD, OR 1m USD)
- 401(k), Traditional IRA and Roth IRA retirement accounts, with different tax treatment from UK pensions and ISAs
- FATCA reporting under IRC ss.1471-1474 plus the UK-USA IGA (2012) creates a dual reporting overlay running in parallel to the DTA
Treaty key features
- UK-USA DTA 2001 is the most-litigated bilateral in HMRC's network
- Article 1(4) saving clause: USA can tax its citizens regardless of other treaty provisions; UK citizens who are not US citizens are not subject
- Article 17(2) pension lump sums: HMRC's March 2025 interpretation change reverses long-held practice for dual UK/US persons (see dedicated page)
- Article 24(6)(c) re-sourcing rule: UK-source income can be re-characterised as US-source for FTC purposes for US citizens UK-resident
- Articles 17 and 18 cover pensions and government service pensions distinctly
- DTA and FATCA operate in parallel; FATCA is not subject to treaty modification
The framework
Residence determination, SRT plus SPT plus tie-breaker →
UK SRT (Schedule 45 FA 2013) determines UK residence; US Substantial Presence Test (IRC s.7701(b)) determines US residence; dual residence is resolved via Article 4 DTA tie-breaker (permanent home, centre of vital interests, habitual abode, nationality, MAP).
UK-USA DTA mechanics plus saving clause →
UK-USA DTA 2001 article-by-article: Article 1(4) saving clause, Article 4 residence, Articles 10/11/12 (dividends, interest, royalties), Articles 13/15/17/18 (gains, employment, pensions, government service), Article 24(6)(c) re-sourcing.
Article 17(2) pension lump sums, March 2025 HMRC change →
Long-held practitioner reading: lump sums from UK pension to US-resident exempt from US tax, UK-taxable only. HMRC March 2025 update asserts the saving clause overrides this for US citizens UK-resident. Practitioner contestation ongoing; verify per specific case.
FATCA plus reporting overlay →
Foreign Account Tax Compliance Act creates parallel reporting obligations: Form 8938 (Statement of Specified Foreign Financial Assets) plus FBAR (FinCEN Form 114). UK-USA IGA (2012) means UK banks report US-person accounts to HMRC and on to the IRS. Independent of the DTA.
UK-USA Social Security Totalization →
Totalization Agreement 1984 prevents double Social Security contributions. Certificate of Coverage mechanism. UK State Pension is uprated in the USA (USA is on the uprated list); US Social Security claimable from the UK.
ISA plus UK savings, the PFIC trap →
IRS does not recognise the ISA wrapper. ISA holdings in unit trusts, OEICs or ETFs typically constitute PFICs (Passive Foreign Investment Companies) under IRC ss.1291-1298, with punitive tax treatment. Stocks and Shares ISAs holding individual UK shares are not PFICs; cash ISAs are not PFICs but interest is fully US-taxable.
UK IHT plus US estate tax interaction →
UK-USA Estate Tax Treaty 1978 (separate from the income tax DTA). US federal estate tax exemption 13.99m USD for 2025 and an increased amount for 2026 under OBBBA (verify). State estate taxes apply in 12 states plus DC. April 2025 UK LTR test changes the UK side dramatically, see /moving-abroad/april-2025-iht-reform-ltr.
Anti-snake-oil, corridor-specific patterns
Pattern: Streamlined Filing Compliance Procedures specialist, 5,000 GBP plus
Reality: IRS Streamlined is a self-serve programme for US persons who failed to file FBAR or 8938. Forms and procedures are publicly available at irs.gov. Genuine dual-jurisdiction CIOT plus AICPA practitioner work is appropriately priced in the 2-5k GBP range for complex cases, not a streamlined-specialist 5k-plus markup.
Pattern: Roth IRA conversion eliminates UK tax
Reality: Wrong. The UK tax position on Roth conversions during UK residency is contested; HMRC view is evolving. Substantive conversion decisions warrant a specialist UK-USA practitioner, not a generic Roth specialist cold pitch.
Pattern: Renounce US citizenship via specialist for 15,000 GBP plus
Reality: Formal renunciation is processed via a US embassy interview with a 2,350 USD fee (announced reduction to 450 USD effective April 2026, verify before reliance). The application process is largely procedural. Specialist counsel is warranted only for complex citizenship-by-descent or tax-status interactions.
Pattern: Self-Directed IRA invests in UK property
Reality: Triggers UBIT (Unrelated Business Income Tax), PFIC issues and prohibited transaction risks. Almost never economically beneficial for retail-tier investors. IRS publications confirm the structural complexity.
Pattern: FBAR amnesty specialist for 5,000 USD plus
Reality: IRS Delinquent FBAR Submission Procedures and Streamlined Filing Compliance Procedures are publicly-documented self-serve programmes. Genuine specialist counsel is warranted for criminal exposure or wilful violations, which are a different mechanic from voluntary disclosure.
Pattern: Dual-filing specialist 8,000 GBP plus retainer
Reality: Qualified dual-jurisdiction UK-USA practitioners exist via CIOT International and AICPA International Tax sections at appropriate 2-5k GBP fees for typical complexity. Cold-pitch firms charging 8k-plus often subcontract or commoditise the work.
Free plus regulated-body resources
- HMRC International Manual (INTM) →
UK-side international tax authority
- IRS Publication 519 (US Tax Guide for Aliens) →
US-side definitive guide
- SSA UK-USA Totalization page →
Definitive totalization agreement reference
- FinCEN Form 114 (FBAR) →
BSA E-Filing System for FBAR
- IRS Streamlined Filing Compliance Procedures →
Self-serve programme for failed FBAR/8938 filings
- CIOT International Tax →
Qualified UK international tax practitioners
- AICPA Tax topic hub →
Qualified US-side practitioners
- MoneyHelper →
Free UK pension and money guidance
Destination-country resources
- US State Department, UK Embassy →
Visa, citizenship and renunciation procedures
- US Citizenship and Immigration Services (USCIS) →
Immigration status mechanics
- American Citizens Abroad (ACA) →
US persons living abroad advocacy and guidance
- IRS UK Tax Treaty documents →
UK-USA DTA full text plus Technical Explanation
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