If you are an American in the UK, you have a problem most accountants cannot solve: you file in two countries whose rules collide. A brilliant UK accountant who does not know US tax, or a US preparer who has never seen a UK pension, can each leave you over-taxed, non-compliant, or both. The right adviser handles both systems together and knows where they interact. This checklist — built from the questions we wish more people asked us — helps you find an accountant who can genuinely manage a dual US/UK position in 2026, and spot the ones who only think they can.
Why 'dual-qualified' thinking matters
The core issue is interaction. A UK ISA is tax-free in Britain but a PFIC nightmare for the US. A UK pension has specific US treaty treatment. The choice between the Foreign Tax Credit and the FEIE changes your bill on both sides. None of these are visible if you look at one country in isolation. So the single most important quality in your adviser is not that they are 'good at tax' — it is that they understand how US and UK rules play against each other, and design your filings around that.
Check 1: genuine credentials on both sides
For the US side, look for an Enrolled Agent (EA) or US CPA — people licensed to prepare US returns and represent you before the IRS. For the UK side, look for a chartered accountant (ACCA or ICAEW) or a qualified tax adviser. The strongest cross-border firms have both sets of credentials in house, so your US and UK returns are prepared by people who actually hold the relevant qualifications, not a generalist guessing at the other country's rules.
- US: Enrolled Agent (EA) or US CPA — can prepare US returns and deal with the IRS.
- UK: ACCA or ICAEW chartered accountant, or a CTA-qualified tax adviser.
- Ideally both under one roof, so the two returns are coordinated, not siloed.
Check 2: they ask about the awkward stuff
A good cross-border adviser interrogates the things that trip Americans up. In an early conversation they should ask about your UK pension, whether you hold an ISA or UK funds, your foreign bank accounts (for FBAR), any UK company you own, and whether you have a US home or investments. If an accountant does not raise PFICs, FBAR, the FEIE-versus-Foreign-Tax-Credit choice, or your pension treatment, that is a red flag — it usually means they will file the obvious forms and miss the interactions that cost you money or compliance.
Check 3: fixed, transparent fees
Cross-border tax has a reputation for open-ended bills, so insist on clarity. A good firm will quote a fixed fee for your return once they understand your situation, and tell you up front what triggers extra cost (an additional rental, a company, a catch-up filing). You should never be surprised by the invoice. Transparent pricing is also a sign of a firm that has done your kind of case many times — they can quote confidently because they know the work involved.
Check 4: they handle compliance clean-up, not just this year
Many Americans come to a cross-border accountant because they are behind — unfiled returns, missed FBARs, an unreported account. Your adviser should be fluent in the fixes: the IRS Streamlined Filing Procedures for non-wilful catch-up, late-FBAR procedures, and reasonable-cause filings. If a firm only does 'this year's return' and goes quiet when you mention past gaps, they are not equipped for the situation many expats are actually in. The ability to bring you current cleanly is a core competence, not an add-on.
Check 5: they plan, not just file
Filing is backward-looking; planning saves money going forward. The best advisers flag the moves that matter before you make them: structuring investments to avoid PFICs, getting pre-immigration planning right before a move, timing a retirement withdrawal or property sale, and choosing the right remuneration mix if you own a UK company. A purely compliance-focused preparer files what happened; a planner helps shape what happens next so your future bills are lower and your position cleaner.
Check 6: responsiveness and timezone reality
Practical things matter when you live an ocean away from one of your tax systems. Can you reach a real person? Do they understand the expat filing calendar — the automatic June deadline, the October extension, the FBAR date? Will they manage both filing seasons so you are not chasing two sets of deadlines yourself? A firm that genuinely serves US expats in the UK runs on the expat calendar and communicates proactively, rather than leaving you to coordinate two countries' paperwork alone.
Questions to ask on the first call
- Do you prepare both US and UK returns in house, and who holds which qualification?
- How do you handle my UK pension and any ISA or UK funds for US purposes?
- Will you advise on FEIE versus the Foreign Tax Credit for my situation?
- What is your fixed fee for my return, and what would cost extra?
- If I'm behind on filings, can you handle a streamlined catch-up?
- How do you manage the US and UK deadlines across the year?
Watch for these warning signs
- Only US or only UK expertise, with the other side 'subcontracted' invisibly.
- No mention of PFICs, FBAR, or pension treaty treatment.
- Vague or open-ended fees with no fixed quote.
- No process for fixing past non-compliance.
- Slow or one-way communication, especially around deadlines.
The right adviser pays for themselves
Dual US/UK tax is one of the few areas where the right professional genuinely saves more than they cost — through correct credit claims, avoided penalties, smarter investment structuring and clean compliance. The wrong one can leave you double-taxed or exposed without you ever knowing. Use this checklist to separate a true cross-border specialist from a generalist with good intentions. At TaxStone we are built for exactly this — US Enrolled Agents and UK-qualified accountants under one roof, with fixed fees quoted before any work begins.
