US & UK Cross-Border Tax
The US & UK Tax Problems You Might Be Facing
Living between the US and the UK creates one of the most complex tax situations in the world. Conflicting residency rules, LLCs taxed the wrong way, PFIC traps on investments and property structures that trigger double taxation. The solution is rarely more forms. It is a coordinated strategy.
A single incorrect assumption can cost you
- ✓ Dual tax residency in both countries without realising it.
- ✓ An LLC taxed twice, once in the US and again in the UK.
- ✓ PFIC charges that can exceed 40% on UK funds and investments.
- ✓ Mistimed gains triggering FIRPTA or UK Non-Resident CGT withholding on property sales.
- ✓ Most people only discover the danger after HMRC or the IRS sends a letter, when it is costly to fix.
Expat professionals and investors moving between the US and UK face constant confusion. Americans buying UK property and Britons buying US real estate make the same legal and tax mistakes, often by holding assets in personal names without considering the cross-border ramifications in both countries. We fix this with a structured US-UK Expat Tax Blueprint that clarifies residency, entity classification, asset positioning and property exposure, so you pay the right tax, in the right country, once.
The US-UK Expat Tax Blueprint
A four-module advisory framework that fixes the four root causes of double taxation. It is built for US citizens in the UK, UK residents with US investments, global executives with stock compensation, and cross-border property owners.
| Module | What it covers | The outcome |
|---|---|---|
| 1. Residency & domicile positioning | UK Statutory Residence Test, US Substantial Presence Test, treaty tie-breaker rules, where income is taxed and what filings are required. | You avoid accidental tax residency in both countries, the most common and expensive expat error. |
| 2. Entity classification clarity | LLC treatment in the UK (transparent vs opaque), Ltd treatment in the US (PFIC/GILTI risk), partnership classification and correct income flows. | You stop LLCs or Ltds being taxed twice and avoid PFIC or GILTI charges caused by misclassification. |
| 3. Asset & investment positioning | Worldwide income mapping, UK vs US capital gains timing, PFIC avoidance, ISA and OEIC dangers, and efficient asset-holding structures. | You avoid 40%+ PFIC rates and time disposals to reduce tax across both systems. |
| 4. Cross-border property structuring | UK property owned by US residents, US property owned by UK residents, ownership choice, FIRPTA withholding, UK Non-Resident CGT and rental income allocation. | You eliminate unnecessary withholding taxes and structure global real estate properly from day one. |
Who this is for
| You are | The typical risk | What we coordinate |
|---|---|---|
| A US citizen living in the UK | Two tax systems that conflict, with continued IRS filing obligations. | IRS and HMRC reporting, residency alignment and foreign tax credits. |
| A UK resident with a US LLC or US investments | US withholding and UK reporting that pull in different directions. | Entity classification, FIRPTA, and matching IRS and HMRC filings. |
| A global executive with RSUs or stock | Equity taxed at the wrong time in the wrong country. | Sourcing, vesting and disposal timing across both systems. |
| A cross-border landlord or dual resident | Double tax on rent and gains, and uncertain treaty position. | Ownership structure, treaty relief and rental income allocation. |
| An IFA, broker, attorney or CPA | Clients in the corridor needing the other country covered. | A specialist partner so your advice aligns across both regimes. |
For more detail on each situation, open the relevant section below.
US citizens living in the UK
US citizens in the UK must manage two tax systems that often conflict. We keep you compliant in both countries and avoid double taxation with one coordinated strategy.
What we help with
- Coordinating IRS and HMRC reporting correctly
- Aligning US and UK tax residency rules
- Applying foreign tax credits to avoid double taxation
- Structuring employment, property and investments efficiently
- Filing accurate US returns even when tax is already paid in the UK
Common problems we fix
- Assuming UK residency ends US filing obligations
- UK accountants misunderstanding US worldwide taxation
- US CPAs ignoring UK statutory residence rules
- Filing in one country without considering the other
US citizens with UK investments
UK investments are often taxed differently by the IRS, creating confusion and unexpected liabilities. We make sure your UK assets are reported correctly and held efficiently.
What we help with
- Reporting UK property income and gains to the IRS
- Aligning UK investments with the correct US treatment
- Structuring pensions, ISAs and UK funds safely
- Applying treaty reliefs and foreign tax credits
- Identifying high-risk investments before they cause issues
Common problems we fix
- Assuming UK rules automatically apply in the US
- Holding ISAs or UK funds without understanding the US consequences
- Incorrect reporting of foreign rental income or assets
- Paying tax twice through uncoordinated filings
British citizens living in the US
Relocating to the US while keeping UK ties creates complex responsibilities on both sides. We keep both countries’ filings aligned.
What we help with
- Establishing correct US tax residency
- Coordinating HMRC and IRS filing obligations
- Managing UK property, pensions and income correctly
- Preventing mismatched reporting between both systems
- Ensuring both countries recognise the right taxes and reliefs
Common problems we fix
- Assuming UK reporting stops when you move
- Forgetting UK CGT rules on UK property sales
- Not reporting UK income to the IRS
- Applying UK remittance concepts incorrectly in the US
British citizens with US investments
Owning US investments as a UK resident needs careful coordination of US withholding and UK tax. We make sure income and gains are taxed correctly in both countries.
What we help with
- Structuring US investments to reduce UK tax impact
- Claiming foreign tax credits efficiently
- Understanding US withholding rules, including FIRPTA
- Managing rental income, dividends and gains across borders
- Ensuring IRS and HMRC filings match and support each other
Common problems we fix
- Not reporting US income to HMRC
- Failing to reclaim excess US withholding tax
- Using inefficient US property ownership structures
- Confusion over federal vs state tax rules
How it works: our services
Diagnostic call (15 minutes, free)
A 15-minute, no-obligation call to discuss your US and UK tax affairs. Often, talking it through gives reassurance that the matter is being handled, even when there is no instant fix. We discuss options for tax advice and for preparing US or UK returns for you personally or for your companies, then agree the next step, usually a 60-minute consultation.
US Tax ID (ITIN) creation
We provide W-7 ITIN application support. As IRS-authorised Certified Acceptance Agents, we handle identity verification, form preparation and direct IRS communication, including for firms who want to offer ITIN support under their own brand. As a CAA we can certify your passport directly, so you do not post your original to the IRS.
Tax consultations (60 minutes)
A 60-minute consultation with Simon Misiewicz, our US and UK Expat Tax Specialist. Before the call, Simon reviews the notes and documents you upload and prepares a bespoke tax-saving plan. During the call he talks through the solutions and helps you build an action plan you can implement quickly. Afterwards he emails the plan and the video recording, and answers follow-up questions within three working days.
UK company formations
Setting up a UK limited company needs more than a Companies House registration. The structure must align with your residency, income sources and long-term plans.
What we do for you
- Advise on share structure, directors, PSC requirements and ownership
- Register the company with Companies House and HMRC
- Set up corporation tax, PAYE, VAT (if required) and bookkeeping
- Ensure the UK company integrates with US filing and reporting rules
US company formations (LLC or C-Corp)
We work with our partner Doola for clients setting up a US LLC or C-Corporation. The structure must align with your residency and treaty position and integrate with both the IRS and HMRC to avoid double taxation.
What we do for you
- Advise whether an LLC, LLP or C-Corporation suits you best
- Form the entity in the correct state for your business model
- Obtain the EIN and ITIN where required
- Prepare check-the-box elections where needed to prevent double taxation
- Align salary, dividends and profit extraction with your UK position
Set up a US LLC or C-Corp via Doola | US company formation guide
W-8BEN forms to reduce US withholding from 30% to 15%
The W-8BEN lets non-US individuals claim reduced withholding on US income, but only when completed correctly and supported by the right treaty article. We complete it accurately and apply the correct provisions so your withholding can drop from the default 30% to the treaty rate.
What we do for you
- Identify whether you qualify under the US-UK treaty
- Complete and submit the form correctly to the payer or institution
- Apply the correct treaty article so the reduced rate is accepted
- Guide you through US-source dividends, interest, royalties and investment income
Get started today: book a call
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Questions & answers
Do I need to file a US tax return if I live in the UK?
Yes. US citizens and green card holders must file a US tax return every year, wherever they live. UK tax does not replace your US filing obligations, but with the correct foreign tax credits you should not pay tax twice.
How do I stop being taxed twice by both the IRS and HMRC?
US and UK double taxation usually happens when residency, sourcing or entity classification is misaligned. We prepare a coordinated US-UK strategy, apply treaty reliefs correctly and make both returns support each other.
Do UK accountants understand US tax rules?
Most do not. UK accountants generally do not deal with US worldwide taxation, PFIC rules, LLC elections or IRS filing. We specialise in both systems and work alongside your UK accountant to keep everything aligned.
How do I know whether to use an LLC, Ltd or C-Corp?
It depends on your residency, where the income arises and how the other country treats the entity. We assess your situation and structure the company so it is taxed correctly in both jurisdictions.
Do I need to report UK pensions, ISAs or property to the IRS?
Yes. The IRS requires reporting of foreign pensions, investment accounts and assets, even when tax is paid in the UK. We explain exactly what must be disclosed and keep the filings correct and penalty-free.
Can you help with W-8BEN or W-8BEN-E forms?
Yes. We complete the W-8BEN and W-8BEN-E forms for you, apply the right treaty articles and help reduce your US withholding from 30% to the treaty rate where applicable.
What if my previous accountant filed my returns incorrectly?
We review your past IRS and HMRC submissions, identify errors or mismatches and correct them through amended filings, aiming to get you back to full compliance with the lowest possible impact.
Do I need an ITIN or EIN to invest or own property in the US?
Often yes. We advise whether you need an ITIN or EIN and support the whole application as Certified Acceptance Agents, including identity verification without sending original passports to the IRS.
Can you coordinate with my UK accountant, wealth manager or mortgage broker?
Yes. Many clients come through adviser referrals. We work directly with your professional team so advice given in the UK aligns with IRS requirements.
How do I get started?
Book a US and UK Expat Tax diagnostic call. We assess your residency, review your filings, identify risks and outline the steps to a coordinated US-UK strategy.
This page is general information and not advice. Tax rules, rates and thresholds change. Take specialist advice before acting.
