Current issues for US & UK Tax Matters
Most accountants and advisers lack the expertise to confidently handle cross-border US–UK tax cases — and risk losing valuable clients or fees as a result.
For UK accountants, US EAs/CPAs, wealth managers and tax advisers seeking a specialist partner in US–UK cross-border tax.
About Simon Misiewicz
Living between two tax systems (US & UK) should not mean paying tax twice.
Yet for thousands of US and UK expats, investors, and cross-border professionals, this is exactly what happens—often because their accountant understands one jurisdiction but not the other.
I built Optimise Accountants to solve this problem.
I’m Simon Misiewicz FCCA, ATT, EA, CAA, MBA, and I specialise exclusively in US–UK Expat Tax Advisory, helping clients avoid residency traps, double taxation, PFIC penalties, GILTI exposure, and costly property mistakes.
I fix the structure that determines how much tax you pay and where you pay it.
My Story – Why I Created the Expat Tax Blueprint
After working with international clients for more than 20 years, one thing became obvious:
the biggest tax risks weren’t caused by income—they were caused by structure.
I repeatedly saw:
US citizens in the UK accidentally triggering PFIC tax charges of 40%+
UK directors setting up US LLCs and getting hit with double tax and GILTI
Clients becoming dual tax-resident without realising
Cross-border property investors paying unnecessary tax on sales
Expats receiving letters from HMRC/IRS after years of filing incorrectly
I created the US–UK Expat Tax Blueprint to provide a clear, step-by-step method to prevent these issues before they happen.
What I do
I clarify whether you are tax-resident in the UK, the US, or both, using SRT, SPT, treaty tie-breakers, and income-sourcing rules.
Your outcome:
✔ Correct residency status
✔ No double taxation
✔ Correct filings in each country
I assess whether your LLC, Ltd, partnership or hybrid setup is tax-efficient and compliant in both jurisdictions.
Your outcome:
✔ No PFIC/GILTI traps
✔ No double tax on company profits
✔ Correct flow-through or corporate treatment
I map your worldwide income, investments, and capital gains so UK/US timing mismatches and PFIC issues are avoided.
Your outcome:
✔ Correct tax treatment of global assets
✔ Optimised timing of disposals
✔ Tax-efficient investment structure
I advise on cross-border US & UK property ownership investors, rental income rules, FIRPTA, NRCGT, and ownership vehicles.
Your outcome:
✔ Understand the US/UK tax treatment of income & gains
✔ Correct US/UK CGT treatment
✔ Optimal long-term structure
✔ Minimise FIRPTA & withholding taxes
Who I work with & My Qualifications
I specialise in helping:
US citizens living in the UK struggling with PFIC and dual-residency issues
UK residents with US companies or investments
Expats with RSUs, stock options, and global income streams
Cross-border landlords and property investors
High-net-worth individuals with multi-jurisdiction assets
Professionals relocating between the US and UK who need pre-arrival planning
If you have income, assets, or property connected to both countries, you will benefit from the structured clarity this blueprint provides.
US & UK Tax Qualifications to support you
FCCA – Chartered Certified Accountant
ATT – Association of Tax Technicians
EA – US Enrolled Agent
CAA – Certified Acceptance Agent (ITIN applications)
MBA – Strategic Finance & International Business
This dual-qualification pathway is rare—fewer than 1% of accountants hold expertise in both US and UK cross-border tax strategy.
