American expat in the UK discussing HMRC and IRS tax obligations with a US and UK tax adviser

American Expats and UK Tax Obligations

For American expats living in the UK, tax can quickly become more complicated than expected. Moving to Britain does not always mean leaving the US tax system behind. At the same time, living, working or investing in the UK may create obligations with HMRC.

This means many American expats need to think about two tax systems at once: the United States tax system and the United Kingdom tax system. Each has its own rules, filing requirements, deadlines, definitions and reporting obligations.

Whether you are employed in London, self-employed in the UK, running a business, receiving investment income, renting property, or planning a long-term move, it is important to understand your tax position properly.

Good tax awareness can help you avoid missed filings, unexpected penalties, double taxation concerns and unnecessary stress.

Why American Expats Need to Think About UK Tax

The UK tax system can apply to American expats in several ways. If you live in the UK, work in the UK, own UK property, earn UK-source income, or become UK tax resident, HMRC may expect you to report income, gains or other financial activity.

Some American expats assume that because they are US citizens, their main tax responsibility is only to the IRS. Others assume that if they pay UK tax, they no longer need to file anything in the United States. Both assumptions can be dangerous.

The reality is that your tax obligations depend on your personal circumstances. Your residence status, income sources, employment arrangement, bank accounts, investments, business interests, pension arrangements and family situation may all affect what needs to be reported.

For this reason, American expats in the UK should not rely on guesswork. The interaction between HMRC and IRS requirements needs careful attention.

UK Tax Residence

One of the most important starting points is UK tax residence. The UK has a specific system for deciding whether someone is resident for tax purposes. This is known as the Statutory Residence Test.

Your UK tax residence position can affect whether you pay UK tax on UK income only or whether foreign income and gains may also need to be considered. The number of days you spend in the UK is important, but it is not the only factor. Work, accommodation, family and other ties may also be relevant.

This is particularly important for American expats who travel regularly, move part-way through the year, retain a home in the United States, work remotely, or have income in more than one country.

The UK tax year runs from 6 April to 5 April. This is different from the US calendar tax year, which can make filing and tax planning more complicated for Americans.

UK Tax on Employment Income

Many American expats in the UK are employees. If you work for a UK employer, income tax and National Insurance may be deducted through PAYE. This can make the UK side of your employment tax position appear straightforward.

However, PAYE does not automatically deal with every tax requirement. You may still need to complete a UK Self Assessment tax return if you have additional income, foreign income, rental income, capital gains, self-employment income, directorship income or other reportable matters.

You should also remember that UK employment income may still need to be reported on your US tax return. The fact that your salary has been taxed in the UK does not automatically mean it can be ignored for US purposes.

UK Self Assessment

Self Assessment is HMRC’s system for collecting tax from individuals whose full tax position is not dealt with automatically through PAYE.

American expats may need to file a UK Self Assessment tax return if they are self-employed, a partner in a business partnership, a landlord, a company director, have capital gains, receive untaxed income, or have other circumstances that require reporting.

For American expats, UK Self Assessment should be considered alongside US tax filing. The same income may need to be reviewed under both systems, but the calculations and tax treatment may not be identical.

This is one reason why cross-border tax advice is so important. Filing in one country without considering the other can create inconsistencies or missed opportunities for tax relief.

UK Tax on Foreign Income and Gains

American expats often retain financial connections to the United States. These may include US bank accounts, brokerage accounts, pensions, retirement accounts, stock options, rental properties, business interests or family trusts.

If you are UK tax resident, foreign income and gains may need to be considered for UK tax purposes. This can include income from overseas employment, rental income, dividends, interest, pensions and capital gains.

The treatment will depend on your residence position, the source of income, the type of asset, the tax year involved and any relevant reliefs. This area can be especially complex for American expats because US tax treatment and UK tax treatment may differ.

For example, a US investment that appears tax-efficient from a US perspective may not be treated the same way in the UK. Similarly, the sale of an asset may produce different calculations under US and UK tax rules.

US Tax Obligations Do Not Automatically Disappear

American expats should also remember that the US generally continues to tax its citizens and resident aliens on worldwide income, even when they live abroad.

This means a US citizen living in the UK may still need to file a US federal tax return. Depending on their circumstances, they may also need to consider state tax, foreign account reporting, foreign asset reporting and other IRS forms.

This can surprise American expats who have lived in the UK for many years and assumed that they no longer had US filing obligations. In many cases, the obligation to file may remain even if no US tax is ultimately due after foreign tax credits or other reliefs are applied.

Foreign Tax Credits and Double Taxation

One of the biggest concerns for American expats is double taxation. Nobody wants to pay tax twice on the same income.

The US and UK systems include mechanisms that may reduce the risk of double taxation, including Foreign Tax Credits and treaty-based provisions. However, these mechanisms need to be used correctly.

The UK may tax income in one way, while the US may classify or calculate that same income differently. Timing differences, exchange rates, deductions, credits and reliefs can all affect the outcome.

This is why it is important to prepare US and UK tax filings in a coordinated way. The aim should be to comply with both systems while reducing unnecessary double taxation where lawful relief is available.

FBAR and Foreign Account Reporting

US expats in the UK should also be aware of foreign account reporting requirements. Ordinary UK bank accounts may be considered foreign accounts for US reporting purposes.

If the combined value of foreign financial accounts exceeds the relevant threshold at any point during the calendar year, an FBAR filing may be required. This can apply even if the accounts are not generating income and even if no additional US tax is owed.

Accounts that may need to be reviewed include UK current accounts, savings accounts, investment accounts and certain other financial accounts.

FBAR is one of the areas most commonly overlooked by American expats. The penalties for non-compliance can be serious, so it is important to take advice if you are unsure whether the rules apply to you.

Property, Investments and Pensions

American expats in the UK should also take care when dealing with property, investments and pensions.

Buying or selling UK property may create UK tax reporting requirements. Selling US property while living in the UK may also have UK tax implications. Investment portfolios can create income, gains and reporting issues in both countries.

Pensions and retirement accounts can be particularly complex. A pension arrangement that is familiar in the United States may need special consideration in the UK. Equally, UK pension contributions or withdrawals may have US tax consequences.

Before making major financial decisions, American expats should consider whether both HMRC and IRS rules have been reviewed.

Common Mistakes American Expats Make

Common mistakes include assuming that UK tax replaces US tax, ignoring US filing obligations, missing FBAR filings, failing to register for UK Self Assessment, misunderstanding UK tax residence, selling assets without tax advice, failing to report foreign income, and using an adviser who only understands one tax system.

Another common mistake is waiting until there is a problem. Cross-border tax issues are often easier to manage when advice is taken early. Once deadlines have passed or returns have been filed incorrectly, the process can become more stressful and expensive.

Why Specialist US/UK Tax Advice Matters

American expats in the UK need tax advice that understands both sides of the Atlantic. UK-only advice may miss IRS obligations. US-only advice may miss HMRC requirements.

A specialist US/UK tax adviser can help identify filing obligations, review residence status, prepare US federal and state tax returns, handle UK Self Assessment, advise on FBAR, consider Foreign Tax Credits, review foreign income and gains, and provide practical guidance for expats with cross-border financial lives.

Tax compliance should not be treated as an afterthought. For American expats, good advice can provide clarity, reduce risk and help ensure both HMRC and IRS obligations are properly managed.

Contact Xerxes Associates LLP

If you are an American expat living, working or investing in the UK, Xerxes Associates LLP can help you understand your tax obligations.

Xerxes Associates LLP is a London-based firm of specialist US and UK tax advisers. The firm provides tax advice and accountancy services for US and UK expats, including US federal and state income tax returns, UK Self Assessment tax returns, personal tax planning, consultations, FBAR assistance and ITIN support.

To discuss your circumstances, contact Xerxes Associates LLP using the details below:

Xerxes Associates LLP
Warnford Court
29 Throgmorton Street
London
EC2N 2AT
United Kingdom

Telephone: +44 (0)207 411 9026
Alternative Number: +44 (0)207 411 9051
Email: info@xerxesllp.com
Website: xerxesllp.com

If you are unsure whether you have UK tax obligations, US tax obligations, or both, it is better to seek specialist advice before a filing issue arises.

London-based US expat reviewing HMRC and IRS tax documents with a specialist tax adviser

London-Based US Expats and HMRC Requirements

London is one of the most popular cities in the world for international professionals, entrepreneurs, investors and high-net-worth individuals. For US citizens and American expats, moving to London can create excellent career, business and lifestyle opportunities. However, it can also create tax responsibilities that should not be ignored.

Many US expats living in London understand that they may still have responsibilities to the IRS. What is sometimes less clear is how HMRC requirements apply once they become UK resident, work in the UK, own UK assets, receive foreign income, or have investment and business interests.

If you are a US citizen, green card holder or American expat based in London, it is important to understand that your UK tax position may need to be considered alongside your continuing US tax reporting obligations. This is where professional US/UK tax advice can make a major difference.

Why HMRC Requirements Matter for US Expats in London

HMRC is responsible for collecting tax in the UK. If you live, work or conduct business in London, you may fall within the UK tax system depending on your residence status, income sources and personal circumstances.

A common mistake among US expats is assuming that UK tax only applies if they are permanently settled in the UK. In reality, UK tax obligations can arise much sooner than expected. Your time spent in the UK, accommodation, employment, family connections and working pattern can all affect your position.

Another common mistake is assuming that because the United States taxes citizens abroad, the UK position is secondary. That is not the case. If you are UK tax resident or have UK-source income, HMRC may still expect appropriate reporting and payment.

For London-based US expats, the real issue is not simply “US tax or UK tax?” In many cases, the issue is how both systems interact.

Understanding UK Tax Residence

One of the first questions for a US expat in London is whether they are UK tax resident. The UK uses the Statutory Residence Test to determine residence for each tax year.

The UK tax year runs from 6 April to 5 April. This is different from the US tax year, which normally follows the calendar year. This difference alone can create confusion when preparing returns, calculating income periods, matching tax credits and understanding filing deadlines.

The Statutory Residence Test considers several factors. These may include how many days you spend in the UK, whether you work full-time in the UK, whether you have accommodation available, whether you have family in the UK, and whether you have other ties to the country.

For many American expats, UK tax residence is not always obvious. Someone may move to London part-way through the year, travel frequently, work remotely, retain a US home, or have income and assets in more than one country. In these situations, tax residence should be reviewed carefully.

Employment Income and PAYE

Many US expats in London are employed by UK businesses, international firms, financial institutions, technology companies, law firms, consultancies or global organisations. If you are employed in the UK, your employer will usually operate PAYE, which means income tax and National Insurance may be deducted from your salary before you are paid.

For straightforward employees, PAYE may deal with much of the UK employment tax position. However, PAYE does not always mean there is nothing else to do.

You may still need to file a UK Self Assessment tax return if you have additional income, high income, rental income, investment income, capital gains, foreign income, self-employment income, directorship income, or other reporting requirements.

US expats should also remember that employment income taxed in the UK may still need to be reported on a US tax return. The fact that tax has been deducted by HMRC does not automatically remove the IRS reporting requirement.

UK Self Assessment for US Expats

Self Assessment is the system used by HMRC to collect tax from individuals whose tax affairs are not fully dealt with through PAYE.

A US expat in London may need to register for Self Assessment and file a UK tax return if their circumstances require it. This can include situations where they are self-employed, have rental income, receive untaxed income, are a company director, claim certain reliefs, receive foreign income, or have capital gains to report.

For Americans in London, Self Assessment can become more complex because the same income may also need to be considered for US tax purposes. This does not automatically mean tax will be paid twice, but it does mean the reporting must be handled properly.

Foreign Tax Credits, tax treaty provisions and the timing of income recognition may all need to be reviewed carefully.

Foreign Income and HMRC

London-based US expats often have financial connections outside the UK. These may include US bank accounts, investment portfolios, retirement accounts, rental property, business interests, stock options, pensions or trusts.

If you are UK tax resident, foreign income and gains may need to be considered for UK tax purposes. The treatment will depend on your residence status, domicile position, the type of income, whether income or gains are remitted to the UK, and the rules in force for the relevant tax year.

This is an area where generic advice can be risky. A US expat with US investments may have one set of issues. A business owner may have another. A person with US pensions, stock options or property income may require a different approach again.

The important point is that HMRC requirements should be reviewed before assumptions are made.

Capital Gains and Asset Sales

US expats in London should also be careful when selling assets. This may include selling shares, cryptocurrency, property, business interests or investments.

Both the UK and US may have tax rules that apply to capital gains. The calculation methods, reporting dates, reliefs and tax treatment may differ between the two countries. This can create unexpected results if advice is not taken before a sale.

For example, a gain may be calculated differently for UK and US purposes. Exchange rates may also affect the final position. The timing of a sale can matter, especially where the individual has recently arrived in or left the UK.

Before selling major assets, London-based US expats should consider taking professional advice to avoid unnecessary tax complications.

UK and US Double Taxation Concerns

Many American expats worry about being taxed twice. This concern is understandable. However, the US and UK tax systems include mechanisms that may reduce double taxation, including foreign tax credits and treaty-based considerations.

The challenge is that these mechanisms must be used correctly. It is not enough to assume that because tax was paid in the UK, the US position will automatically be correct. Equally, it is not safe to assume that filing in the US means HMRC has no interest.

A coordinated approach is often needed. US and UK tax returns should be prepared with awareness of each other, especially where income, credits, deductions, pensions, investments or gains overlap.

FBAR, FATCA and UK Accounts

US expats living in London often open UK bank accounts, savings accounts and investment accounts. These accounts may create US reporting obligations, even if the accounts are ordinary UK accounts used for everyday living.

The FBAR may be required where the aggregate value of foreign financial accounts exceeds the relevant threshold at any point during the calendar year. FATCA-related reporting may also need to be considered depending on the value and type of foreign financial assets.

This is separate from HMRC reporting, but it is highly relevant to US expats in the UK. A London-based American may therefore need to consider UK tax filing, US tax filing and foreign account reporting at the same time.

Why London-Based US Expats Should Seek Specialist Advice

US expat taxation in London is not only about filing forms. It is about understanding the interaction between HMRC requirements and IRS obligations.

A London-based US expat may need help with UK tax residence, UK Self Assessment, US federal tax returns, US state tax questions, FBAR, FATCA, Foreign Tax Credits, Foreign Earned Income Exclusion, pensions, investments, property, business ownership and capital gains.

Using separate advisers who do not understand the other tax system can lead to gaps, duplication or missed planning opportunities. For this reason, many US expats prefer to work with advisers who understand both US and UK tax compliance.

Contact Xerxes Associates LLP

If you are a US expat living or working in London and need help understanding your HMRC requirements and US tax obligations, Xerxes Associates LLP can assist.

Xerxes Associates LLP is a London-based firm of specialist US and UK tax advisers. The firm provides tax advice and accountancy services for expats living in the United Kingdom and the United States, including US federal and state income tax returns, UK Self Assessment tax returns, FBAR and ITIN assistance, tax consultations, personal tax planning and cross-border tax support.

To discuss your circumstances, contact Xerxes Associates LLP using the details below:

Xerxes Associates LLP
Warnford Court
29 Throgmorton Street
London
EC2N 2AT
United Kingdom

Telephone: +44 (0)207 411 9026
Fax / Alternative Number: +44 (0)207 411 9051
Email: info@xerxesllp.com
Website: xerxesllp.com

If you are unsure whether HMRC requires you to file a UK tax return, or whether your London-based income and assets create US reporting issues, it is better to seek advice early.

ABOUT US

Xerxes Associates LLP was established by Naveed Lasi after having gained over a decade of industry experience with EY, Deloitte and PwC.

ADDRESS

Warnford Court, 29 Throgmorton St, London, EC2N 2AT, UK

CONTACTS

Call Us: Tel: +44 (0)207 411 9026

Fax: +44 (0)207 411 9051

E-mail Us: info@xerxesllp.com

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