American Tax Accountant UK: What They Prepare Each Year

American tax accountant UK: an introduction

An American tax accountant UK residents hire prepares the US federal return, the US foreign account reports and, ideally, the UK Self Assessment return as well. Americans in Britain file in both countries every year, because the US taxes citizens wherever they live. The real job is making the two returns agree, so the same income is not taxed twice.

This article sets out what that work covers and how to judge it. Our guide to US and UK tax returns explains the full annual cycle in more depth. You can also see our US federal returns and UK Self Assessment service pages.

Why an American tax accountant UK side is different

A UK accountant knows HMRC, and a US preparer knows the IRS. However, an American in the UK needs both at once. For example, a UK pension, an ISA and a London flat each have different US and UK treatment. Therefore, an American tax accountant UK clients rely on must understand how one country's figures feed the other's. Without that, credits are lost or claimed twice.

What does an American tax accountant in the UK prepare?

Each year, the core filings are Form 1040, the FBAR and, where thresholds are met, Form 8938. On the UK side, the core filing is the Self Assessment return, if HMRC requires one.

The US federal return

Form 1040 is the annual US income tax return. According to the IRS page for US citizens and resident aliens abroad, citizens report worldwide income wherever they live. To avoid double tax, the return usually claims one of two reliefs. The foreign earned income exclusion removes earned income up to a limit from US tax. For 2026, Revenue Procedure 2025-32 sets that limit at $132,900. Alternatively, the foreign tax credit, claimed on Form 1116, offsets UK tax against US tax.

Choosing between the exclusion and the credit

For most people in the UK, the foreign tax credit works better. UK income tax rates reach 45%, according to GOV.UK's page on Income Tax rates. Consequently, UK tax often exceeds the US tax on the same income. Excess credits can then carry forward. However, the exclusion can suit lower earners or people with few other credits. A good American tax accountant UK side will model both before choosing, because changing later has limits.

FBAR and Form 8938

The FBAR is the report of foreign financial accounts filed with FinCEN. The IRS FBAR page says you file one when your foreign accounts together exceed $10,000 at any time in the year. Form 8938 is a separate IRS form for specified foreign financial assets. Its thresholds are higher for people living abroad. The IRS Form 8938 page links to the instructions. Our article on Form 8938 for Americans abroad gives the figures.

The forms people miss

Some UK holdings trigger extra US forms. For instance, UK unit trusts and many ISA funds count as passive foreign investment companies, reported on Form 8621. Similarly, some UK trusts need Form 3520. Owning a UK company can require Form 5471. Moreover, a treaty position may need disclosing on Form 8833. Each carries its own penalty for late filing, so the annual review should look for them.

When are the US and UK deadlines?

The US return is due on 15 April, with an automatic two months for citizens abroad. The UK online return for 2025 to 2026 is due on 31 January 2027.

US deadlines

The IRS gives citizens living abroad an automatic two-month extension to 15 June. However, interest on unpaid tax still runs from 15 April. You can extend further, to 15 October, by filing Form 4868. Separately, the FBAR is due on 15 April, with an automatic extension to 15 October. Our article on US tax deadlines for Americans abroad covers the detail.

UK deadlines

GOV.UK lists the Self Assessment deadlines. For the 2025 to 2026 tax year, paper returns are due by 31 October 2026. Online returns and payment are due by 31 January 2027. Additionally, if you have never filed before, you must register for Self Assessment by 5 October after the tax year ends.

Why the order matters

The UK tax year runs from 6 April to 5 April, while the US year is the calendar year. Therefore, US credits depend on UK figures that straddle two UK years. In practice, we usually finalise the UK return first. The US return then claims the right amount of UK tax as a credit. This sequence is the heart of what an American tax accountant UK clients need actually does.

Why must the two returns agree?

The returns must agree because each country's relief depends on the tax shown in the other. If they disagree, you may pay twice or face questions from either side.

Double tax relief

Double tax relief is the credit one country gives for tax paid to the other. GOV.UK explains how to claim relief if you are taxed twice. The US-UK treaty sets out which country taxes first for each kind of income. Consequently, the source of each item decides which return gives the credit. Our guide to the US-UK double taxation treaty explains the rules.

Exchange rates and timing

The US return is in dollars, and the UK return is in pounds. Each item must be converted at a consistent rate. The IRS publishes yearly average currency exchange rates that many preparers use. However, gains on property or shares often need the rates on the purchase and sale dates. Getting this wrong can create phantom gains, which is a common error.

What if you have missed US returns?

You catch up, usually through the IRS Streamlined procedures, before anything else. Many Americans in the UK only learn about US filing years after they arrive.

How common it is

In our experience, a large share of new enquiries come from people who have never filed from the UK. Often, a UK bank sends a FATCA letter asking for a US tax number. Sometimes a new partner or a mortgage application raises the question. Either way, the first job for an American tax accountant UK clients bring this to is to find out how many years are missing. The second is to check whether any US tax is actually due.

The Streamlined route

The Streamlined Filing Compliance Procedures let non-wilful filers catch up with three years of returns and six years of FBARs. Non-wilful means the failure came from negligence, mistake or a good faith misunderstanding. For people living abroad, the foreign offshore version carries no penalty when every instruction is followed. Our pillar guide to IRS Streamlined filing explains eligibility and the certification you sign.

Why late FBARs need care

Filing old FBARs on their own is not a penalty-free fix. The IRS removed its page on delinquent FBAR submissions in July 2026. Therefore, we file late FBARs as part of a recognised route, such as Streamlined, rather than in isolation. Furthermore, missing information returns, such as Form 8938 or Form 8621, are brought up to date in the same package.

Does every American in the UK need a Self Assessment return?

No. Many employees taxed fully through PAYE never receive a notice to file. However, Americans in the UK often have income that PAYE does not cover.

When a UK return is needed

Common triggers include rental income, self-employment, foreign income and capital gains above the annual exempt amount. Similarly, HMRC asks some higher earners to file even when PAYE covers their pay. US income, such as US dividends or a US rental, is often the trigger for Americans. In those cases, the UK return and the US return must both show the same income.

When a UK return helps even if not required

Sometimes a UK return is useful even when HMRC has not asked for one. For example, it can record foreign tax already paid or claim reliefs that PAYE missed. However, an American tax accountant UK clients use should explain why before registering you. Registration creates an ongoing duty to file until HMRC confirms otherwise.

How do you choose an American tax accountant in the UK?

Ask what they will prepare on both sides, how they handle the credit calculation and what they need from you. Check, too, that they hold an IRS preparer number.

Check the basics

The IRS explains how to start choosing a tax professional. Anyone paid to prepare US returns must hold a Preparer Tax Identification Number. A PTIN is the number the IRS issues to paid preparers. The IRS sets out the PTIN requirements in detail. Additionally, ask whether the firm prepares the UK return itself or hands it to someone else.

Questions worth asking

First, ask whether they file both returns from one set of figures. Next, ask how they treat UK pensions and ISAs on the US return. Then ask how they deal with funds that count as PFICs. Finally, ask how they handle missed years, if you have any. A clear answer on each shows experience with American clients in Britain.

Outside London

Many Americans in the UK live far from London, in Edinburgh, Bristol, Cambridge or the countryside. Cross-border returns do not need a face-to-face meeting. Documents arrive by email, and questions are answered in writing. Therefore, an American tax accountant UK clients use can serve anywhere in the country equally well. Our article on finding a US tax accountant in London covers the capital specifically.

What should you send your accountant each year?

Send your P60, any P11D, bank interest figures, pension statements, investment reports and last year's returns. The more complete the first pack, the fewer follow-up questions.

Employment and pensions

Your P60 is the end-of-year certificate from your employer. GOV.UK explains the P60 and related forms. Because the US year differs, we may also need payslips for March and December. Furthermore, workplace pension statements show contributions and values for the US forms.

Accounts and investments

List every account you held during the year, including closed ones, with the highest balance for each. This feeds the FBAR and Form 8938. For investments, send annual statements showing income, purchases and sales. Similarly, send details of any ISA, because the US does not recognise its tax-free status.

An example

Consider a typical case. Sarah is a US citizen who teaches in Edinburgh. She has a salary, a workplace pension, a cash ISA and a small US brokerage account. Each spring, she emails her P60, pension statement, ISA interest and account balances.

Her accountant first prepares her UK return, since Scottish tax on her salary is the main credit. Next, the US return claims that tax through Form 1116. Then her FBAR lists four accounts, and Form 8938 is checked against the abroad thresholds. As a result, Sarah owes no US tax, and her two returns agree line by line. This is an illustrative example, not a real client.

How US UK Tax Experts can help

US UK Tax Experts prepares US and UK returns from one file, so the two agree. That covers Form 1040, the FBAR, Form 8938, the credit calculations and UK Self Assessment. Additionally, we review each year for the extra forms that UK pensions, funds and companies can trigger. We work by email with clients across the UK. If you need an American tax accountant UK side who looks at both returns together, we can help.

Conclusion

Americans in the UK file two sets of returns every year, on two different tax years. The work that matters is making them agree, so relief is claimed once and in the right place. Choose someone who prepares both sides, asks about your pensions and funds, and explains the order of work. Then the annual cycle becomes routine.

Contact us

If you are looking for an American tax accountant UK based clients trust to handle both returns, email hello@usuktaxexperts.com or use our contact form. Tell us where you live, what you earn from and whether your past returns are up to date. We reply within one working day.