Financial Planning for British Expats in the USA: Complete Guide 2026

The United States is home to a substantial British expat community — drawn by career opportunities, family ties, and the scale of the American economy. However, the US tax system stands apart from almost every other country in the world: it taxes not only residents but also citizens on their worldwide income, regardless of where they live or earn. For British nationals moving to the US, this creates a complex and often costly compliance landscape that demands careful financial planning before departure and throughout the duration of any stay.

This guide sets out the key financial and tax considerations for British expats in the USA as of 2026. Given the complexity of US tax law, specialist advice from a qualified cross-border adviser is strongly recommended for your personal circumstances.

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Why the US Is Unlike Almost Anywhere Else

Most countries tax residents on their worldwide income — that is standard internationally. What makes the United States unusual is that it also taxes its citizens on worldwide income, no matter where they live. The only other country to apply citizenship-based taxation in this way is Eritrea.

For a British national who becomes a US citizen or a Lawful Permanent Resident (Green Card holder), this means US tax obligations follow them wherever they go — even if they later leave the US and return to the UK.

This is not merely a theoretical concern. British expats who obtain a Green Card and subsequently move back to the UK may find themselves still subject to US filing obligations and, in some cases, US tax — even while paying UK income tax as a UK resident. Careful tax planning around the timing and nature of US status is therefore essential.

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The US Tax Burden: Federal, State, and Social Security

The federal income tax rate in the US rises progressively, with top rates applying to the highest income bands — the marginal rate at the top of the scale represents a substantial effective rate for high earners. On top of federal tax, most states levy their own income tax, with rates varying considerably: some states have no income tax at all, while others (including California and New York) impose rates that can push the combined federal and state marginal rate above 50% for high earners.

Social Security contributions (known as FICA — the Federal Insurance Contributions Act) apply to earned income. Employees contribute a fixed percentage of their earnings (up to Social Security wage base limits), with a further contribution for Medicare. These are not optional for US employees.

For British expats on secondment or working under US employment contracts, the combined federal, state, and Social Security burden can represent a materially higher effective tax rate than the equivalent UK position. Pre-move tax modelling is highly advisable.

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Social Security Numbers, ITINs, and Filing Requirements

To work legally in the United States, you need a Social Security Number (SSN). Your employer will require it, and it is used across most financial and government interactions. British nationals entering on work visas will typically apply for an SSN through their employer sponsorship process.

For British nationals who are in the US but do not have the right to work — for example, accompanying a partner on a dependent visa — an Individual Taxpayer Identification Number (ITIN) may be required if they have US tax filing obligations (for example, if they have US-source investment income). The ITIN is not a work authorisation; it is purely a tax filing identifier.

US tax returns must be filed annually, typically by mid-April for the prior tax year. Extensions are available, but any tax due is still payable by the original deadline. British expats abroad may qualify for an automatic extension of time to file, but not an extension of time to pay.

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The UK-US Double Tax Treaty

The UK and the US have a comprehensive double taxation agreement (DTA) that is designed to prevent the same income from being taxed in full by both countries. In general terms:

• UK-source income (such as a UK salary, UK rental income, or UK pension) is taxed first in the UK; the US then allows a credit for the UK tax paid, reducing the US liability on the same income.
• US-source income is primarily taxed in the US; a UK credit is available for UK residents on US-source income.

However, the treaty contains an important "saving clause": the US reserves the right to tax its own citizens and Lawful Permanent Residents as if certain treaty provisions did not exist. This means that some of the treaty's protective provisions may not fully apply to Green Card holders or US citizens, and the interaction between the treaty and US domestic law can be highly complex. The treaty's pension articles and the treatment of UK pensions for US persons are particularly nuanced areas.

Specialist advice on treaty positions is essential — do not assume that the treaty fully resolves your position without confirmation from a qualified adviser who understands both US and UK tax law.

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FBAR and FATCA: Foreign Account Reporting

Two sets of reporting obligations apply to US residents and citizens with financial accounts outside the United States:

FBAR (Foreign Bank Account Report — FinCEN Form 114) If the aggregate value of all your foreign financial accounts exceeds $10,000 at any point during the calendar year, you must file an FBAR with the Financial Crimes Enforcement Network (FinCEN). "Foreign financial accounts" includes any non-US bank account, brokerage account, pension fund, ISA, offshore bond, or similar financial interest.

Filing is electronic and separate from your tax return. Failure to file carries civil penalties that can be substantial per violation per year. Wilful failure to file can result in even more severe consequences.

FATCA (Foreign Account Tax Compliance Act — Form 8938) FATCA requires US taxpayers with specified foreign financial assets above certain thresholds to report those assets on Form 8938, attached to their tax return. The thresholds are higher than FBAR (typically starting at $50,000 for single filers living in the US, with higher thresholds for those living abroad), but the two obligations are separate — filing one does not satisfy the other.

For British expats moving to the US, their entire UK financial footprint — savings accounts, investment ISAs, SIPP, offshore bonds, premium bonds, and so on — may fall within these reporting requirements. Getting the compliance framework right from day one is far easier than remediation later.

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UK ISAs: A Significant Problem for US Persons

The UK Individual Savings Account (ISA) is one of the most effective tax wrappers available to UK residents: income and gains within an ISA are free of UK tax. However, the IRS does not recognise the ISA's tax-exempt status.

For US persons (citizens, Green Card holders, or US residents), the IRS may treat an ISA as a foreign grantor trust, requiring annual reporting on Form 3520 (Annual Return To Report Transactions With Foreign Trusts and Receipt of Certain Foreign Gifts) and potentially Form 3520-A. The income and gains within the ISA are taxable in the US on an arising basis.

The compliance burden associated with UK ISA ownership for a US person can be disproportionate. As a result, many British expats who become US residents or citizens choose to close their UK ISAs before triggering US person status — retaining the investments outside the ISA wrapper instead. This is a decision to review with a specialist in advance of any move.

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UK Pensions and US Persons

UK pensions — including workplace schemes and Self-Invested Personal Pensions (SIPPs) — generally have treaty protection under the UK-US DTA. UK pension income paid to a US resident is typically taxable in the US (as the country of residence), with credit available for any UK withholding tax. In practice, most UK pension income does not have UK tax withheld at source for non-residents who complete the appropriate forms.

The treatment of QROPS (Qualifying Recognised Overseas Pension Schemes) for US persons is particularly complex. Most QROPS jurisdictions are not US tax treaty partners, and the tax treatment of QROPS transfers for US persons can be highly unfavourable. As a result, QROPS is rarely an appropriate solution for British expats moving to the United States. In most cases, retaining a UK SIPP and managing it as a UK-domiciled pension is the more prudent approach — though expert advice is essential.

Pension lump sum payments are treated differently from ongoing pension income under the treaty, and the applicable article requires careful reading in the context of your specific circumstances.

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Visa Routes to the USA

British nationals have a range of visa options depending on their circumstances:

• H-1B: For specialty occupation workers — typically requiring at least a bachelor's degree. Subject to an annual cap and lottery process, making it competitive.
• L-1: For intracompany transfers — employees of multinational companies who transfer to a US affiliate, subsidiary, or parent. L-1A for managers/executives, L-1B for specialised knowledge workers.
• O-1: For individuals with extraordinary ability in sciences, arts, education, business, or athletics. Less common, but not subject to the H-1B lottery.
• EB-5 Investor Visa: A route to a Green Card through direct investment in a US commercial enterprise. Minimum investment amounts apply, with lower thresholds for Targeted Employment Areas. The EB-5 programme is a legitimate but lengthy process.
• Green Card (Lawful Permanent Residence): Granted through employment sponsorship, family sponsorship, the Diversity Lottery, or through EB-5. Once obtained, a Green Card holder is a US person for tax purposes.
• US Citizenship: Available generally after five years of continuous lawful permanent residence (three years if married to a US citizen). US citizenship brings the full weight of citizenship-based taxation.

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The "Accidental American" Problem

British parents who give birth to a child in the United States may unknowingly create a US citizen. By the principle of birthright citizenship (jus soli), any person born on US soil is automatically a US citizen — regardless of the parents' nationality. These "accidental Americans" acquire all the attendant US tax filing obligations from birth, including FBAR and FATCA requirements once they hold their own financial accounts.

This is a well-documented issue affecting many British families and creates complex succession and financial planning challenges. If you have children born in the US or believe your children may be US citizens, specialist advice on their status and obligations is important.

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Relinquishing US Citizenship

For those who have acquired US citizenship and find the compliance burden unacceptable — particularly those who have returned to the UK and have no intention of living in the US again — relinquishment of US citizenship is an option. The process involves:

• A formal renunciation before a US consular officer
• A government fee (reduced from $2,350 to $450 with effect from April 2026)
• A potential "exit tax" under Internal Revenue Code Section 877A, which applies to "covered expatriates" — those meeting income, net worth, or compliance thresholds. The exit tax operates as a deemed mark-to-market disposal of all assets on the day before expatriation, with tax levied on unrealised gains above an annual exclusion amount.

Relinquishment is irreversible. It is not a step to take without significant deliberation and specialist legal and tax advice. For some individuals, however, particularly those with no ongoing connection to the United States, it is a considered and rational choice.

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Key Financial Planning Actions Before Moving to the USA

1. Obtain specialist cross-border tax advice — from an adviser qualified in both UK and US tax. This is not an area where generalist guidance is sufficient.
2. Review your UK ISA holdings — consider whether to close ISAs before triggering US person status, reinvesting the proceeds in unwrapped accounts.
3. Understand your UK pension position — assess whether your existing pension structure is US-treaty-compliant and what the US tax treatment of withdrawals will be.
4. Map your foreign financial accounts — identify all accounts that will need to be reported under FBAR and FATCA from day one of US residency.
5. Consider the state of destination — the state-level income tax varies significantly; this affects your overall effective tax rate.
6. Review protection and estate planning — US estate tax applies to US-situated assets and to the worldwide estates of US citizens; UK inheritance tax can interact with this in complex ways.
7. Clarify your visa timeline and Green Card implications — understand at what point you become a "US person" for tax purposes and what that triggers.

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How Global Investments Can Help

At Global Investments, we work with British expats navigating some of the world's most complex financial environments. The United States presents unique challenges — from FBAR and FATCA compliance to the interaction of the UK-US treaty with your pension and ISA holdings — and the cost of getting it wrong can be significant.

We connect clients with qualified cross-border advisers with dual expertise in UK and US tax and financial planning, coordinate with specialist US tax attorneys where needed, and help ensure that your investment and pension structures are properly designed for your US residency before you relocate.

Please note: this guide is for general information only and does not constitute tax or legal advice. US tax law is subject to change and the rules governing your personal position depend on your specific circumstances. Professional advice should always be obtained before making decisions based on this content. The value of investments can fall as well as rise, and you may receive back less than you invest.