US & UK Tax Preparation & Compliance

Accountants for US and UK Taxes — One Firm for Both Returns

Accountants for US and UK taxes prepare your IRS return and your HMRC Self Assessment as one coordinated piece of work — so tax paid on one side offsets tax on the other, nothing is reported twice, and nothing is missed. We are dual-qualified specialists in US and UK taxation for Americans in Britain, dual citizens, accidental Americans, high-net-worth individuals, investors, founders and cross-border businesses.

Accountants for US and UK taxes are dual-qualified specialists who prepare your US federal return (Form 1040) and your UK Self Assessment together, using the US-UK tax treaty, the Foreign Tax Credit and correct FBAR, FATCA and PFIC reporting to keep you compliant on both sides without paying tax twice. Preparing the returns in the right order — UK figures feeding the US credit — is what a genuine specialist does that a generalist cannot.

Key Takeaways

US citizens and green card holders file US returns for life, wherever they live — the UK residence rules run in parallel.
The treaty and Foreign Tax Credit stop double taxation; the saving clause means you still file a full US return.
UK ISAs and funds are usually PFICs (Form 8621); UK accounts trigger FBAR and often Form 8938.
One firm handling both sides prevents the gaps that appear when a US and a UK accountant work separately.

US and UK tax return preparation under one roof

If you are American and living in the UK — or British with US income, a green card, or a life that straddles both countries — you sit inside two tax systems that were never designed to talk to each other. The United States taxes its citizens on worldwide income no matter where they live. The United Kingdom taxes you on the basis of residence. Left unmanaged, the two overlap, contradict and duplicate, and the result is either tax paid twice or filings quietly missed. Accountants for US and UK taxes exist to make the two systems work as one.

A true dual-handling firm prepares both returns from a single, consistent set of figures. Your UK income and the UK tax you have paid feed directly into the US Foreign Tax Credit, your US positions are checked against the treaty, and every international form — FBAR, Form 8938, Form 8621, Form 5471 — is completed once, correctly, and in step with the other side. That coordination is the whole point, and it is precisely what you lose when a UK accountant and a US preparer work in isolation.

Who needs a US-UK accountant?

Cross-border tax is not only a problem for the wealthy or the self-employed. If either country has a claim on your income, you probably need someone who can see both sides at once.

Americans and green card holders living in the UK

US citizens and lawful permanent residents keep filing US returns for life, wherever they live. Move to the UK and you simply add a second system on top — UK Self Assessment alongside the US 1040 — with the two reconciled through the treaty and the credit.

Dual US-UK citizens and “accidental Americans”

Dual citizens, and people who are American only by an accident of birth or parentage, are full US taxpayers even if they have never lived in the States. Many discover this only when a UK bank sends a FATCA letter. If you are years behind, the IRS Streamlined Filing route is designed for exactly this situation.

Brits in the US and people moving across the Atlantic

UK nationals with US income, those relocating in either direction, and secondees all face split-year treatment, residence questions and social-security coordination. Getting the first year right — before habits and elections are set — saves years of correction later.

High-net-worth individuals, investors, founders and businesses

Investment portfolios, UK companies, carried interest, share schemes and property make the filing genuinely technical. Our high-net-worth and business and corporate teams handle the forms — Form 5471, GILTI, PFICs — that generalist accountants rarely touch.

Why you must file in both countries: worldwide income vs residence

The two systems clash because they start from different premises. The US taxes on citizenship — as the IRS confirms, American citizens and resident aliens abroad are taxed on worldwide income. The UK taxes on residence, determined by the Statutory Residence Test. Live in the UK as a US citizen and both claims apply to the same income at the same time. Filing in both countries is therefore not optional or a duplication — it is the mechanism through which each country grants relief for the other's tax. Skip one side and you forfeit the very reliefs that stop you paying twice.

Avoiding double taxation: the US-UK treaty, FEIE and Foreign Tax Credit

You should not pay full tax twice on the same income, and with the returns prepared properly you will not. Three tools do the work, and choosing between them is where preparation turns into planning.

The saving clause and what it means for US citizens

The US-UK income tax treaty contains a “saving clause” that preserves the United States' right to tax its citizens as though most of the treaty did not exist. This is why the treaty relieves double taxation but never removes your obligation to file a US return — a distinction that trips up people who assume the treaty lets them opt out of the IRS.

FEIE (Form 2555) vs Foreign Tax Credit (Form 1116) — which we use and why

The Foreign Earned Income Exclusion removes a band of earned income from US tax; the Foreign Tax Credit credits the UK tax you have already paid against your US bill. Because UK rates are generally higher than US rates, the credit usually wins for people in the UK and even builds a carry-forward — while the exclusion can quietly cost you the refundable Child Tax Credit. We model both on your figures rather than defaulting to whichever is quicker to prepare.

Treaty-based positions and Form 8833

Some benefits — particularly around pensions and specific income types — depend on taking a treaty position and, where required, disclosing it on Form 8833. Getting the disclosure right protects the benefit and avoids penalties.

Order of operations: which return we prepare first, and why it changes the result

This is the part almost every competitor gestures at and almost none explain. Because UK tax paid becomes the Foreign Tax Credit on the US return, the UK numbers generally have to be settled first — the US return is built on top of them. Prepare the US return in a vacuum and the credit is guesswork: income can be double-counted, the wrong category used on Form 1116, or a treaty re-sourcing position missed that would have freed up a credit otherwise wasted. The sequence — UK figures first, then a US return that consumes them correctly — is the single biggest reason a dual-handling firm beats two separate accountants on the final number, not just on convenience.

US and UK tax return preparation — Form 1040 and HMRC Self Assessment prepared together by cross-border accountants — US and UK returns prepared from one set of figures — the UK position feeds the US Foreign Tax Credit.

Your US filing obligations we prepare

The US side is form-heavy, and the international forms are where inexperienced preparers go wrong.

Form 1040 and US state returns — your federal return, plus any state that still considers you a filer after you left.
FBAR (FinCEN 114) — reports foreign accounts once their combined high balance tops 10,000 dollars. See the IRS FBAR guidance. Model exposure with our FBAR penalty calculator.
FATCA / Form 8938 — reports specified foreign financial assets above the abroad thresholds; see About Form 8938. It overlaps with, but does not replace, the FBAR.
PFICs and Form 8621 — the ISA and UK fund trap — most UK funds and stocks-and-shares ISAs are PFICs, taxed punitively and reported per fund on Form 8621.
Foreign corporations: Form 5471, GILTI and CFCs — for founders and owners of UK companies; see About Form 5471.

Your UK filing obligations we prepare

Self Assessment and the SA100 series

We register you where needed and prepare the SA100 return with the supplementary pages your income requires — employment, self-employment, UK property, foreign income and capital gains — through our UK tax services.

Residence and the Statutory Residence Test (SRT)

Whether you are UK resident is not a matter of opinion — it is decided by HMRC's Statutory Residence Test, which weighs days in the UK against your ties here. We run it before preparing anything, because it determines what the UK can tax.

Domicile, the remittance basis and the 2025 FIG regime

From 6 April 2025 the UK abolished the non-dom remittance basis and moved to a residence-based system with a four-year Foreign Income and Gains regime for new arrivals — see the current GOV.UK guidance on tax on foreign income. If you have arrived recently, this reshapes your UK position and how your US credits apply.

Pensions across the border: SIPPs, workplace schemes and the treaty

UK pensions are one of the treaty's most valuable features and one of its most misunderstood. Handled correctly, a SIPP or workplace scheme can generally grow without current US tax and be taxed mainly where you live — but the UK 25 percent tax-free lump sum is not automatically tax-free to the IRS, and US retirement accounts held by someone now in the UK need their own treatment. This is detail work, and detail is where money is saved or lost.

Investments and savings: ISAs, funds and the reporting that trips people up

The hardest truth for many new clients is that the UK's best tax shelters are US tax problems. A stocks-and-shares ISA is tax-free to HMRC but fully taxable to the IRS, and the funds inside it are usually PFICs. General Investment Accounts, investment trusts and most UK-domiciled funds carry the same issue. We identify every holding, apply the right PFIC election where it helps, and report each one properly rather than hoping the IRS does not notice.

Cross-border US-UK tax documents — FBAR, FATCA Form 8938 and PFIC reporting for Americans in the UK — FBAR, FATCA and PFIC reporting on UK accounts, ISAs and funds — completed in step with both returns.

Property on both sides: UK rental, US capital gains and the mortgage FX gain

Property is where cross-border surprises cluster. UK rental profit is taxed on both returns with a credit for the UK tax, but the US profit figure differs because depreciation is mandatory in the States. When you sell a UK main home, the UK's full Private Residence Relief has no US equivalent beyond a 250,000-dollar exemption (500,000 for a couple), so a large gain can create US tax with no UK tax due. And under Section 988, paying off or remortgaging a sterling mortgage in a strong-dollar year can trigger a US foreign-currency gain on its own. Almost no competitor page warns you about the last two.

Behind on filing? Streamlined Filing and catch-up

If you have missed years of US returns or FBARs, the IRS Streamlined Filing Compliance Procedures let non-wilful taxpayers abroad get fully compliant — three years of returns, six years of FBARs and a certification — usually with no penalties. We handle these routinely through our Streamlined Foreign Offshore Procedures service; you can size the position first with our Streamlined Filing calculator.

Common US-UK tax mistakes we fix

Treating a UK ISA or fund as tax-free on the US return and omitting the PFIC forms.
Preparing the US return before the UK numbers, then miscalculating the Foreign Tax Credit.
Filing three years of FBARs instead of six in a catch-up, invalidating the submission.
Assuming the treaty removes the US filing obligation because of the saving clause.
Missing the Section 988 gain on a remortgaged UK property, or US tax on a UK home sale.
Using the Foreign Earned Income Exclusion by default and losing the refundable Child Tax Credit.

Specialist vs general accountant vs DIY software

Capability	US-UK specialist	General accountant	DIY software
Prepares both US and UK returns	Yes	One side only	One side only
Coordinates the Foreign Tax Credit across both	Yes	Rarely	No
Handles PFICs / Form 8621 on ISAs and funds	Yes	Usually not	No
Form 5471 / GILTI for UK companies	Yes	Rarely	No
Applies treaty positions (incl. Form 8833)	Yes	Rarely	Limited
Section 988 FX and UK home-sale gains	Yes	Rarely	No
Fixed-scope fee, both sides quoted together	Yes	Varies	Flat but incomplete

How our engagement works, step by step

Consultation — we map your income, accounts, property and companies across both countries.
Fixed-scope quote — a clear fee for the exact returns and forms you need, agreed before work starts.
Document gathering — a precise checklist; we chase nothing you have already sent.
Coordinated preparation — UK figures first, then the US return built on them, with every international form.
Review, approval and filing — you see both returns together before anything is submitted.
Year-round support — the same team for questions, planning and next year.

How our fees work — transparent, fixed-scope pricing

We quote a fixed fee up front, scoped to your situation, so you know the cost before you commit. A straightforward employed dual filer is at the lower end; a founder with a UK company, a share portfolio and rental property is higher because the work — Form 5471, multiple Form 8621s, FX calculations — is genuinely greater. The quote always covers the US return, the UK return and the specific international forms in play, with no hourly surprises. Most competitors hide this; we would rather you could plan.

How to choose a US-UK accountant: the credentials to look for

Genuine dual capability is rarer than the marketing suggests. Look for US preparation by a CPA or IRS Enrolled Agent (verifiable in the IRS directory), UK preparation by an ACA, ACCA or CTA-qualified accountant, and demonstrable, routine experience of FBAR, FATCA, PFICs, Form 5471 and the treaty. Ask directly whether the same firm prepares both returns or sub-contracts one side, and whether the fee is fixed. A general UK accountant cannot optimise — or even sign — a US return, and US expat software cannot prepare your Self Assessment. Only a specialist closes the gap between the two.

Why us-uktax.com

We are dual-qualified accountants for US and UK taxes, with offices in London, New York and San Francisco, working exclusively on cross-border cases. Both returns are prepared in-house by the same team, in the right order, with every international form handled as routine rather than outsourced or avoided. Explore our US tax services, UK tax services, cross-border tax planning and our companion pillar on tax specialists for US and UK.

Key US and UK tax deadlines at a glance

UK tax year: 6 April to 5 April. Online Self Assessment due 31 January.
US tax year: calendar year. Return due 15 April, automatically extended to 15 June for Americans abroad, and to 15 October on request.
FBAR: due with the US return, with an automatic extension to 15 October.

Book a consultation Tax specialists for US and UK →

Accountants for US and UK — Frequently Asked Questions

Do US citizens and dual citizens living in the UK have to file taxes in both countries?

Yes. The United States taxes its citizens and green card holders on worldwide income wherever they live, so a US person in the UK files a US federal return (Form 1040) every year, while the UK taxes them as a resident through Self Assessment. Most people end up inside both systems at once, which is exactly what a US-UK accountant exists to reconcile.

Do I still file a US return even if I owe no US tax after credits?

Almost always, yes. The Foreign Tax Credit or Foreign Earned Income Exclusion frequently reduces the US bill to zero, but the filing obligation is separate from the tax obligation — you still have to file the return, and often FBAR and Form 8938, to claim those reliefs and stay compliant. Owing nothing is not the same as filing nothing.

Do I need to file a UK Self Assessment return, and how does the Statutory Residence Test decide?

You file UK Self Assessment if you are UK resident with untaxed income, are self-employed, have foreign income, or HMRC issues you a notice to file. Whether you are UK resident is decided by the Statutory Residence Test, which weighs days spent in the UK against ties such as work, family and accommodation. We run the test for you before we prepare anything.

When are the US and UK tax deadlines, and what extensions are available?

The UK Self Assessment year runs to 5 April, with online returns due by 31 January. The US year is the calendar year: returns are due 15 April, automatically extended to 15 June for Americans abroad, and to 15 October on request. FBAR follows the US return with an automatic October extension. The two calendars rarely line up, which is one reason coordinated preparation matters.

Which return should be prepared first — US or UK — and does the order change what I owe?

Usually the UK return (or at least the UK numbers) comes first, because UK tax paid becomes the Foreign Tax Credit that offsets US tax on the same income. Prepare the US return in isolation and you can misstate the credit, double-count income, or miss a treaty re-sourcing position. Getting the sequence right is a large part of what a genuine US-UK accountant does.

Will I be taxed twice on the same income?

Generally no. The US-UK tax treaty and the Foreign Tax Credit are designed so that tax paid in one country offsets tax due in the other, so the same pound of income is not taxed twice over. Double taxation usually only appears when returns are prepared separately and the credits are not claimed correctly — which is a preparation failure, not an unavoidable outcome.

How do US-UK dual citizens avoid double taxation?

Through a combination of the Foreign Tax Credit (Form 1116), the Foreign Earned Income Exclusion (Form 2555) where appropriate, and specific treaty articles. The right mix depends on your income types: UK employment income is often best handled with the credit because UK rates are high, while treaty positions handle pensions and certain other items. We model the options rather than defaulting to one.

Does the US-UK tax treaty mean I don't have to file a US return?

No. The treaty relieves double taxation and assigns taxing rights, but the treaty's saving clause specifically preserves the United States' right to tax its own citizens as if the treaty did not exist. So a US citizen in the UK still files a full US return; the treaty changes what you owe and how items are treated, not whether you file.

Should I use the Foreign Earned Income Exclusion or the Foreign Tax Credit?

For most Americans in the UK the Foreign Tax Credit is the stronger choice, because UK tax rates are generally higher than US rates, leaving excess credits to carry forward. The Foreign Earned Income Exclusion can suit people with low UK tax or specific circumstances, but it does not cover investment income and can block the Child Tax Credit. We compare both on your actual numbers.

Do I need to formally claim the treaty (Form 8833) to get relief?

Sometimes. Many treaty benefits are claimed simply by how the return is prepared, but certain positions must be disclosed on Form 8833 to be valid and to avoid penalties. Knowing which positions require disclosure — and drafting that disclosure so it holds up — is a routine part of preparing a cross-border return correctly.

What is FBAR (FinCEN 114) and do I need to file it?

The FBAR, FinCEN Form 114, reports your non-US financial accounts to the US Treasury. You must file if the combined high balance of all your foreign accounts exceeded 10,000 US dollars at any point in the year — a threshold most people in the UK cross easily once current accounts, savings, ISAs and pensions are added together. It is separate from your tax return and carries steep penalties if ignored.

What are the FATCA / Form 8938 thresholds for people in the UK?

Form 8938 reports specified foreign financial assets under FATCA and has higher thresholds than FBAR that vary by filing status and residence. For Americans living abroad the reporting threshold starts at 200,000 US dollars of such assets on the last day of the year, or 300,000 at any point, and doubles for joint filers. Form 8938 and the FBAR overlap but are not the same form, and many people must file both.

Do I have to report my UK ISAs and pensions to the IRS?

Yes. An ISA is tax-free in the UK but not to the IRS, so the income inside it is usually taxable on your US return and the account is reportable on the FBAR and often Form 8938. UK pensions are also reportable, though the treaty offers meaningful protection for how the growth and contributions are taxed. Both are common tripwires that generalist accountants miss.

Are UK ISAs and investment funds a PFIC problem, and what is Form 8621?

Very often, yes. Most UK funds, investment trusts and stocks-and-shares ISAs are Passive Foreign Investment Companies (PFICs) in US eyes, taxed under a punitive regime and reported on Form 8621 — one form per fund, per year. This is one of the most technical areas of a US-UK return and a frequent reason DIY software and UK-only accountants get returns badly wrong.

Why am I suddenly getting FATCA letters from my UK bank?

Under FATCA, UK banks and platforms identify customers who are US persons and report their account details to HMRC, which shares them with the IRS. A letter asking for your US taxpayer information means your bank has flagged you — it is routine, not an accusation, but it does mean your accounts are visible to the IRS, so quietly ignoring US filing is no longer a realistic option.

How are UK pensions (SIPP, workplace, State Pension) taxed for Americans under the treaty?

The US-UK treaty generally lets UK pensions grow without immediate US tax and taxes most pension income only in your country of residence, with specific rules for lump sums and the UK 25 percent tax-free amount, which the US does not automatically treat as tax-free. Workplace and personal pensions, SIPPs and the State Pension each have their own treatment, so the detail matters.

How is my UK rental income taxed on my US return?

UK rental profit is taxable in both countries, but you report it on both returns and claim a Foreign Tax Credit for the UK tax paid, so you are not taxed twice. The US calculation differs from HMRC's — depreciation is mandatory on the US side and the allowable expenses are not identical — so the profit figure on each return is rarely the same number.

Do I owe US capital gains tax when I sell my UK home?

Possibly. The UK gives full Private Residence Relief on your main home, but the US only exempts up to 250,000 dollars of gain (500,000 for a couple) and taxes the rest. A large UK gain can therefore create a US tax bill even when no UK tax is due — and there may be a separate US taxable gain on paying off the mortgage in a strong dollar year. This catches many people out.

What is the foreign-currency gain on paying off a UK mortgage, and can it create US tax?

Under Internal Revenue Code Section 988, the US treats a foreign-currency mortgage as a separate transaction. If the dollar has strengthened against sterling between taking out and repaying (or remortgaging) the loan, you can realise a taxable foreign-currency gain in US dollars even though nothing seems to have happened in pounds. It is a genuine, and genuinely surprising, exposure on UK property.

How does the end of the non-dom remittance basis and the new 2025 FIG regime affect me?

From 6 April 2025 the UK abolished the non-domicile remittance basis and replaced it with a residence-based system, including a four-year Foreign Income and Gains (FIG) regime for new arrivals that can exempt qualifying foreign income and gains for a limited period. If you have recently moved to the UK, or plan to, this reshapes both your UK position and how your US credits interact with it.

I'm only in the UK short-term — does that change my US or UK filing?

It can. Short-term secondees may not become UK tax resident under the Statutory Residence Test, or may qualify for the new four-year FIG regime, while social security is often protected by the US-UK totalization agreement so you keep paying into one system, not both. The US filing obligation continues regardless, but the UK side and the credit planning can look very different.

What happens if I haven't filed US taxes in years while living in the UK?

You are far from alone, and there is a designated route back. The IRS Streamlined Filing Compliance Procedures let non-wilful taxpayers abroad file three years of returns and six years of FBARs with no penalties, provided you come forward before the IRS contacts you. It is usually the cleanest and cheapest way to fix years of missed filing.

What is the Streamlined Filing procedure and does it remove penalties?

The Streamlined Foreign Offshore Procedures are an IRS programme for Americans abroad whose failure to file was non-wilful. You submit three years of tax returns, six years of FBARs and a certification of non-wilfulness, and qualifying filers pay a 0 percent offshore penalty — only the actual tax due plus interest. It closes once the IRS opens an examination, so timing matters.

If I give up US citizenship, do I still owe US tax (exit tax / Form 8854)?

Renouncing citizenship does not erase past obligations, and 'covered expatriates' above certain net-worth or tax thresholds can face a US exit tax on unrealised gains, reported on Form 8854. You also generally need several years of compliant filing before renouncing. It is a significant, irreversible step that should only be taken after the numbers are modelled properly.

Do you handle US business owners with foreign companies (Form 5471, GILTI, CFCs)?

Yes. A US person who owns or controls a UK company usually has to file Form 5471, and may face GILTI and Subpart F inclusions on the company's profits under the controlled foreign corporation rules. This is among the most complex parts of cross-border tax and a core part of our business and founder work, coordinated with the UK corporation tax position.

How much does a US-UK accountant cost and how do your fees work?

We quote a fixed, scoped fee before any work starts, based on the returns and forms your situation actually needs — a straightforward employed dual filer costs far less than a founder with a UK company and a share portfolio. You will not be surprised by hourly creep; the quote reflects the US return, the UK return and the specific international forms in play.

What credentials should a genuine US-UK specialist hold, and how are you different from a general accountant?

Look for genuine dual capability: US preparation by a CPA or IRS Enrolled Agent, UK preparation by an ACA, ACCA or CTA qualified accountant, and real experience of FBAR, FATCA, PFICs and the treaty. A general UK accountant cannot sign or optimise a US return, and US expat software cannot prepare your Self Assessment — a specialist handles both sides so nothing falls between them.

Can I hire you for just one side (only my UK or only my US return), and what documents do you need?

Yes — many clients come to us for the US side while an existing UK accountant handles Self Assessment, or vice versa, and we coordinate with them. Either way we start from your prior returns, income documents (P60/P45, payslips, 1099s, W-2s), account statements for FBAR, pension and investment paperwork, and details of any property or company. We give you a precise checklist up front.

Authoritative sources

Written & reviewed by the US-UK Tax Advisors cross-border tax team — chartered specialists in US and UK taxation, IRS and HMRC compliance, FATCA/FBAR reporting and double-taxation treaty planning.

Last reviewed: July 2026. This page is for general information and is not personal tax advice.