Accountants for US and UK Taxes: What a Dual-Qualified Firm Does, What It Costs and How to Choose

Accountants for US and UK taxes are needed by anyone the IRS and HMRC can both reach in the same year. That is a larger group than it sounds. The United States taxes its citizens and green card holders wherever they live; the United Kingdom taxes anyone resident here on worldwide income, and non-residents on UK-source income such as rent. Put those two rules together and a surprising number of ordinary people, not just executives, have two returns to file and one set of facts that has to be reported consistently on both.

Americans and green card holders living in the UK

Every US citizen in Britain files a US return each year, whether or not any US tax is due, and most will also need to file a UK Self Assessment return at some point: when they have savings or investment income over £10,000, rental income, self-employment, or simply because HMRC asks. We set out how we work with Americans living in the UK, and the tax obligations of Americans living in the UK lists both sides form by form. A green card holder who moves back to Britain keeps US obligations until the card is formally surrendered; see green card holders living abroad.

British citizens living in the US

A Brit who becomes a US tax resident, on a work visa, a green card or through the substantial presence test, is taxed by the US on worldwide income, including UK rental profits, UK dividends and, in some cases, the growth inside a UK pension. UK-source income such as rent from a flat in Leeds still needs a UK return as a non-resident landlord. There is more on how we help Brits living in the US, and the tax guide for Brits moving to the US covers the first year.

Dual citizens and accidental Americans

Someone born in the US who left as a child, or born in Britain to an American parent, is a US citizen for tax purposes and has always been one. Dual citizens file in both countries; accidental Americans who have never filed usually have a clean route back through the Streamlined procedures, explained in tax for accidental Americans.

Founders, landlords and the self-employed with income in both countries

A UK limited company owned by a US citizen is a controlled foreign corporation for US purposes, with Form 5471 and possibly net CFC tested income (the regime called GILTI before 2026); founders with companies on either side need both returns planned together. A US LLC owned by a UK resident is treated as a company by HMRC and as transparent by the IRS, which creates double tax if nobody plans for it. Landlords with property on either side face two sets of property rules; see UK rental income as a US citizen. Remote workers and contractors working across the border have to work out where their services are taxed before anything else.

When you probably do not need one

A US citizen visiting Britain for a few months with no UK income has nothing to file here. A British person who has never lived or worked in the US and holds no US assets has nothing to file there. An American in the UK with employment income only, no investments and no pension events could, in a quiet year, manage with software. The first year, and any year with a move, a property sale, an inheritance or a new investment, is not a quiet year.

A UK accountant prepares your Self Assessment return. A US accountant prepares your Form 1040. Accountants for US and UK taxes do both, and, more importantly, do the work in between: deciding which return is prepared first, carrying the UK tax figure into the US foreign tax credit, taking the same position on the same pension under the US–UK tax treaty on both returns, and reporting the same accounts to FinCEN and to HMRC without contradiction.

The US side

• Form 1040 and any state return, with the state residency question settled before you leave a state, not after.
• Form 1116 (foreign tax credit) or Form 2555 (foreign earned income exclusion, $132,900 for 2026), modelled rather than defaulted.
• The FBAR, filed with FinCEN when non-US accounts exceed $10,000 in aggregate, and Form 8938 when specified foreign assets exceed the thresholds for filers abroad ($200,000 at year end or $300,000 at any time for a single filer; double for joint filers, per the IRS comparison).
• Form 8833 for treaty positions, Form 8621 for each PFIC in an ISA or UK fund, Forms 5471 and 8858 for UK entities, Form 3520 for UK trusts and large gifts.

The UK side

• Self Assessment: the SA100 with the SA106 foreign pages, the SA109 residence pages and the SA105 property pages, plus registration by 5 October if you are new to it.
• Residence under the Statutory Residence Test and split year treatment in a year of arrival or departure.
• Claims under the four-year Foreign Income and Gains regime where they help, and advice not to claim where they would simply shift tax to the IRS.
• Payments on account, the PAYE coding interaction, and from 6 April 2026 Making Tax Digital for Income Tax for sole traders and landlords with qualifying income over £50,000.

The coordination work

Sequencing comes first: for a UK resident, the UK year to 5 April is finalised before the US return, so the US return uses real UK tax, not an estimate. Exchange rates come from one documented rate table for the year, applied to both returns. Treaty positions must match: a SIPP protected under Article 18 on the US return is described the same way on the UK one.

Households need the same care. Where an American is married to a non-US spouse, the couple's joint accounts and income are reported so that the two spouses' returns do not contradict each other. Account lists are built once and used for the FBAR, Form 8938 and the SA106 pages. For a full year of this work, month by month, read what US UK tax accountants do.

Many firms in this market describe themselves as "dual-qualified". The phrase has a precise meaning and a loose one. Precisely, it means an individual holds a recognised US tax credential and a recognised UK one. Loosely, it means the firm employs some people with each. Both can serve you well. What you need to know is which you are getting, and that the two sides work on the same file.

Whoever prepares a US return for a fee must hold an IRS Preparer Tax Identification Number and sign the return; ask who that will be. HMRC does not license tax advisers, but since 18 May 2026 anyone paid to deal with HMRC on a client's behalf must register with HMRC as a tax adviser and meet its minimum standards, with existing agents registering in phased windows. Registration is not a qualification, so membership of a professional body (CIOT, ATT, ICAEW or ACCA) remains the main check of competence on the UK side, and it brings a complaints process and compulsory insurance with it.

The IRS explains preparer credentials on its own site, and who does what among CPAs, EAs, CTAs and ATTs goes further. For what each credential proves and what it does not, see our guide to tax specialists for US and UK.

Fees in this market vary widely, and complexity is priced by the form, not by your income. The ranges below are our illustration of how complexity drives cost, not a price list or a survey.

Two rules protect you: a fixed fee in writing before work starts, and a scope that names the forms included. Hourly billing on cross-border compliance rewards slow research. VAT at 20% is added to fees for clients who belong in the UK; clients who belong outside the UK are usually outside the scope of UK VAT (VAT Notice 741A). A consultation before engagement is normal; whether it is free, credited against the fee, or charged varies by firm. For a quote on your own facts, tell us your situation.

1. Discovery call. Citizenship, visas, dates of moves, employers, accounts, pensions, property, businesses, prior filings on each side.
2. Written scope and fixed fee. Which returns, which forms, which years.
3. Residence and strategy. Statutory Residence Test result, US residence tests for non-citizens, treaty tie-breaker if needed; foreign tax credit versus exclusion; FIG decision; treaty positions on pensions; approach to any PFICs.
4. Documents. The two-column checklist below, uploaded to a portal.
5. UK return first for a UK resident. The SA100 and supplementary pages are finalised and the UK tax figure fixed.
6. US return. Form 1040 with the international forms, the state return if needed, and the FBAR filed separately with FinCEN.
7. Joint review. One reviewer reads both returns side by side: same account list, same rates, same treaty positions.
8. Filing. HMRC submission receipt, IRS e-file acceptance, FBAR acknowledgement.
9. Next year. Payments on account, US estimated payments if relevant, and the changes to make before 5 April.

The dual-country calendar

Sources: GOV.UK Self Assessment deadlines and the IRS page for citizens abroad. The details are in separate posts on the automatic two-month extension and registering by 5 October.

Documents to bring

Illustrative only. They show which forms each situation triggers on each side, not what any individual should do.

A London employee on PAYE with a workplace pension and a stocks and shares ISA. UK: no Self Assessment needed in a plain year, though the ISA and pension are fine for HMRC. US: Form 1040 with Form 1116 wiping out US tax on salary, Form 8833 for the pension's treaty position, FBAR and probably Form 8938 covering the current account, the ISA and the pension, and Form 8621 for each fund held in the ISA. The ISA, tax free in Britain, is the expensive line on the US return.

A US citizen in Manchester who owns a rental flat in Bristol. UK: Self Assessment with the SA105 property pages, and Making Tax Digital quarterly updates once qualifying income, meaning gross rents plus any self-employment turnover before expenses, is over £50,000 (from April 2026) or over £30,000 (from April 2027). US: Schedule E on the same property, with depreciation the UK does not give and a UK mortgage that can produce a currency gain on repayment; Form 1116 on the passive basket; FBAR on the rental account.

A Brit in New York with a flat in Leeds under the Non-Resident Landlord Scheme. UK: non-resident Self Assessment on the rent, with the SA109 pages. US: Form 1040 as a resident, Schedule E on the Leeds flat, Form 1116 for the UK tax, FBAR on UK accounts, and Form 8938 once the thresholds are crossed. New York State and City tax apply from arrival.

• Domicile is gone from UK income and capital gains tax. From 6 April 2025 the remittance basis was replaced by a four-year Foreign Income and Gains regime for people in their first four years of UK residence after ten years away. Claiming it costs the personal allowance. For a US citizen it can simply move tax from HMRC to the IRS, because the US still taxes the income and there is then no UK tax to credit. The trade-off is explained in our guides to the FIG regime and to the non-dom changes for Americans.
• Inheritance tax follows residence. Someone UK resident for ten of the last twenty tax years is a long-term UK resident and within UK inheritance tax on worldwide assets, with a tail of up to ten years after leaving. US estate tax applies to US citizens regardless. The two need planning together; see US/UK trusts and estates.
• Making Tax Digital for Income Tax became mandatory for sole traders and landlords with qualifying income over £50,000 from 6 April 2026, with lower thresholds following in 2027 and 2028.
• US figures. The foreign earned income exclusion is $132,900 for 2026 ($130,000 for 2025); the 2026 standard deduction is $16,100 single and $32,200 married filing jointly. The FBAR threshold stays at $10,000. For tax years beginning after 31 December 2025 the regime for US shareholders of foreign companies formerly called GILTI is renamed net CFC tested income.

UK pensions, SIPPs and the treaty

Growth inside a UK pension is generally protected from US tax by Article 18 of the treaty; the position should be disclosed on Form 8833 (failing to do so when required carries a $1,000 penalty) and reported consistently on both returns. Relief for contributions is narrower and depends on the type of scheme, and the 25% tax-free lump sum is not automatically tax free in the US. See how UK pensions are taxed on a US return and, for the reverse case, how a 401(k) is taxed for UK residents.

ISAs, UK funds and PFICs

The US does not recognise the ISA wrapper, and UK funds inside it are usually passive foreign investment companies taxed under punitive rules on Form 8621. The fixes are set out in why your ISA is a problem on a US return.

Property and the Non-Resident Landlord Scheme

Rent from UK property is taxed in the UK whoever you are, and letting agents withhold tax from non-resident landlords unless HMRC approves gross payment. The US taxes the same rent with its own depreciation rules. Selling a UK home as a US citizen brings the Section 121 exclusion and the currency-gain trap on the mortgage; see our cross-border property service.

Behind on US filing

The Streamlined Foreign Offshore Procedures let non-wilful late filers who meet the non-residency test catch up with three years of returns and six years of FBARs and no penalty. They are closed to anyone whose returns the IRS has opened a civil examination of, for any year, or who is under criminal investigation. Our Streamlined filing service and guide cover who qualifies.

Renunciation

Giving up US citizenship ends future filing but can trigger the exit tax for covered expatriates. It is a decision to make with both returns in view; see the tax implications of renouncing.

Ten questions

1. Who will prepare my US return, who will prepare my UK return, and do they work together on my file?
2. Which US credential and which UK credential does the team hold, and can I verify them?
3. Who signs my Form 1040 as paid preparer?
4. Will you run the Statutory Residence Test and document my residence position?
5. Will you model the foreign tax credit against the exclusion for my figures?
6. How do you deal with the funds inside my ISA?
7. Will you disclose my pension's treaty position on Form 8833?
8. Do you represent clients before both the IRS and HMRC?
9. What is the fixed fee, and exactly what does it include?
10. What is your turnaround in January and in April?

Nine red flags

• A UK quote with no question about US citizenship or green cards.
• "Your ISA is tax free" and nothing about PFICs.
• Advice to skip the FBAR because no tax is due.
• National Insurance credited as income tax on the US return.
• The exclusion and the credit claimed on the same income.
• No written fixed fee.
• "We send the US side to a partner firm" with no named preparer.
• No professional body membership on the UK side or no PTIN on the US side.
• An adviser who is not registered with HMRC as a tax adviser.

A scoring sheet built from these is in comparing US/UK cross border tax services providers fairly, and one firm or two? weighs the alternative of using two separate accountants.

Searches for "US UK accountant near me" assume the work needs a local office. It does not. Both HMRC and the IRS accept electronic filing, documents move through a secure portal, and signatures are electronic. What an office gives you is time-zone coverage and a room for the conversations that deserve one: a move, a renunciation, a company sale, an estate plan.

US/UK Cross Border Tax — US CPAs and UK tax advisers working as one team — works from London (4 Crown Place, EC2A), Manchester (CORE, Brown Street), New York (33 Irving Place) and San Francisco (600 California Street). A client in Edinburgh and a client in Denver get the same US CPAs and UK tax advisers on the same file, and the same fixed fee in writing before any work begins.