US Tax Advice for London Lawyers covering profit shares and cross-border filing US Tax Advice for London Lawyers: A Cross-Border Guide An American lawyer practising in London — whether at a magic-circle firm, a US firm’s London office, or in-house — earns a substantial income that two tax authorities both want to tax. As a […]
An American lawyer practising in London — whether at a magic-circle firm, a US firm’s London office, or in-house — earns a substantial income that two tax authorities both want to tax. As a US citizen, they are taxed by the United States on worldwide income for life; as a UK resident, they are fully inside the UK system as well. The pay can be complex too, especially for partners, whose income is a share of firm profits rather than a salary. US Tax Advice for London Lawyers is the discipline of making those two systems work together cleanly.
This guide explains the cross-border tax picture for American lawyers in London and what good advice should cover.
US Tax Advice for London Lawyers is the combined US and UK tax management of an American legal professional based in Britain. Because the United States taxes its citizens on worldwide income regardless of residence, a lawyer never leaves the US system by moving to London. Because the UK taxes residents on their income and gains, the lawyer is fully inside the UK system too.
The result is two tax returns, two tax years, and two sets of rules applied to one income. The lawyer’s task is to practise law; the adviser’s task is to ensure every element of their reward is reported correctly in both countries and taxed once, not twice. Treating the US and UK filings as one coordinated exercise — rather than two separate jobs done by advisers who never speak — is the foundation of getting this right.
The single most important question in US Tax Advice for London Lawyers is whether the lawyer is an employee or an equity partner. An associate or in-house lawyer is generally an employee, paid a salary and bonus that behave broadly like ordinary employment income in both systems. The analysis, while still cross-border, is relatively contained.
An equity partner is in a different position entirely. A partner does not receive a salary; they receive a share of the firm’s profits, allocated to them whether or not it is fully drawn in cash. That profit share is treated as self-employment or partnership income, and it brings its own timing, its own reporting, and its own interaction between the US and UK systems. A lawyer being promoted into the partnership should treat that promotion as a tax event, not just a career milestone.
For US purposes, the lawyer reports worldwide income on a US return every year. An employee’s salary and bonus are ordinary income. A partner’s profit share flows through on a partnership basis, generally as self-employment income, and can carry self-employment tax considerations that the US-UK social security agreement may affect.
The US also expects extensive information reporting on the lawyer’s UK financial life — accounts, pensions, and investments. Many UK pooled investments are Passive Foreign Investment Companies, which carry their own punitive regime and Form 8621 reporting. The US tax calculation is only part of the work; the information reporting around it is an equally important part.
As a UK resident, the lawyer is taxed by the UK on their income. An employee is taxed on salary and bonus through the UK system as it is received. A partner in a UK LLP is taxed on their share of the LLP’s profits as a self-employed person, reporting through Self Assessment.
The UK’s residence-based rules, reshaped from April 2025, also affect lawyers who have recently arrived in the UK or who have foreign income and gains. The constant theme is interaction: how and when income is characterised and taxed in the UK feeds directly into the US calculation, and any mismatch is where double taxation creeps in.
Most UK and many international law firms operate as limited liability partnerships. For an American partner, the LLP is the heart of the tax picture. The partner is allocated a share of the LLP’s profit, and that allocation — not the cash drawn — is generally what is taxed. A partner can therefore owe tax on profit that has been allocated to them but retained in the firm.
The LLP also has its own profile under US rules. A partner’s interest in a foreign partnership can carry US reporting, and the foreign-sourced income flowing through the LLP must be characterised for US purposes. A magic-circle or international firm with offices worldwide makes this more complex still, because the source of the partner’s profit share can be spread across multiple countries. Untangling that is central to US Tax Advice for London Lawyers at partner level.
The two main tools are the Foreign Tax Credit and the US-UK double tax treaty. Where the same income is taxed by both countries, the credit allows tax paid in one to offset tax due in the other, and the treaty allocates taxing rights and provides relief. Because UK rates are generally higher than US rates on comparable income, a lawyer who pays UK tax first usually finds the US liability substantially reduced.
The relief, however, must be engineered. Credits have to be matched to the right category and year of income, treaty positions claimed correctly, and the social security agreement applied where self-employment income is involved. A timing mismatch — profit taxed by the UK in one year and the US in another — is a classic way the credit fails to line up.
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Report |
Why it catches London lawyers |
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FBAR |
UK current, savings, and investment accounts over the threshold must be reported annually |
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Form 8938 |
Specified foreign financial assets above the limit require FATCA reporting |
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PFICs |
UK funds and ISAs are often PFICs, requiring Form 8621 |
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Foreign partnership reporting |
A partner’s interest in a UK LLP can carry US reporting |
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Pension treatment |
UK pensions need correct treatment under the US-UK treaty |
None of these necessarily creates extra tax, but each carries its own penalty for non-filing, which is why reporting sits at the heart of US Tax Advice for London Lawyers.
Becoming a partner usually means contributing partner capital to the firm, and that contribution — often funded by a loan — has tax dimensions of its own, including how any interest is treated in each country. Drawings, the cash a partner takes during the year, are not the same as the taxable profit share, and confusing the two is a common error.
Many firms also operate deferred or retained profit arrangements, and these can be taxed on different bases in the US and the UK. A partner who treats the cash received as the whole story, ignoring allocated-but-undrawn profit and capital arrangements, can end up with a return that does not reflect reality. Good advice maps capital, drawings, allocations, and any deferred element separately.
The first mistake is using a single-country accountant, leaving half the picture unmanaged. The second is confusing drawings with the taxable profit share, so the return understates income. The third is ignoring PFICs inside UK pensions and ISAs. The fourth is overlooking the reporting that a partnership interest can carry. The fifth is treating a promotion to partner as purely a career event, when it fundamentally changes the tax position and deserves advice in advance.
Consider an American lawyer who has spent years as an associate at a London firm, taxed straightforwardly as an employee, and is now promoted to equity partner. Overnight, her income changes from a salary to a share of LLP profits, she contributes partner capital funded by a loan, and her drawings no longer equal her taxable income.
Sound US Tax Advice for London Lawyers treats the promotion as a planning event. Her adviser characterises the profit share for both the US and the UK, handles the self-employment and social security position, addresses the treatment of the capital loan interest, and ensures the foreign-sourced elements of the firm’s profit are sourced correctly. The Foreign Tax Credit is modelled so the higher UK tax relieves the US liability. She moves into partnership with a clear, coordinated tax position — rather than discovering the complications a year later when two returns no longer agree.
An American lawyer in London builds up UK pensions and savings over a career, and these deserve specific attention in US Tax Advice for London Lawyers. UK workplace and personal pensions are valuable, and the US-UK tax treaty contains provisions affecting how a US person’s pension contributions and growth are treated. Applying those provisions correctly can preserve the pension’s tax-advantaged status as far as the rules allow.
Other UK savings are less forgiving. An ISA receives no equivalent US recognition and usually holds investments the US treats as PFICs, so a lawyer who funds ISAs and UK funds without US advice can quietly create an annual reporting and tax problem. The consistent principle is that every long-term saving decision should be checked against both systems before the money goes in, not after.
Legal careers are mobile — a secondment to a US office, a move between firms, or an eventual return to the United States all change the tax position. The period around any change of residence is one of the most valuable planning windows a lawyer has, because the timing of income recognition and the treatment of partnership interests can be influenced before the move.
Good US Tax Advice for London Lawyers treats a relocation as a planned event. Before an arrival or departure, a lawyer can review which income to recognise and when, and how a partnership interest or capital account will be treated. A move handled with advance advice is an opportunity; one handled afterwards is usually a list of opportunities missed.
A partner’s profit share is generally self-employment income, and self-employment carries social security implications. The US and UK have a social security agreement — a “totalisation” agreement — designed to stop the same earnings being charged to social security in both countries and to determine which system applies.
For an American lawyer who is an equity partner, applying that agreement correctly matters: without it, a partner could face social security charges on both sides of the Atlantic. A specialist confirms which system the partner contributes to and ensures the position is documented, so the social security side of the partnership income is handled as deliberately as the income tax side.
American lawyers in London need advisers fluent in partnership taxation and in both systems. As specialist accountants for US and UK high-net-worth tax, Jungle Tax handles the profit-share analysis, the LLP reporting, and the full set of US information returns.
The firm works as US tax advisors for American expats to keep the US side accurate, and as established accountants in London it understands the legal community its clients work within. The result is a lawyer who can focus on practice, not on reconciling two tax codes.
An American lawyer in London carries two tax systems on every pound of income, and for an equity partner the profit-share structure makes that genuinely intricate. US Tax Advice for London Lawyers turns that complexity into one coordinated, efficient outcome — provided the work is done by advisers who handle the US and UK sides together.
To organise your cross-border position, especially around a partnership promotion, book a meeting with Jungle Tax or email hello@jungletax.co.uk.
US citizenship means worldwide US taxation regardless of UK residence, and a lawyer’s income — especially a partner’s profit share — follows different rules in each country.
A partner is taxed on their share of the firm’s profits, generally as self-employment or partnership income, whether or not the profit is fully drawn in cash.
Drawings are the cash a partner takes during the year; the profit share is the allocated taxable profit. They are often different amounts, and tax follows the profit share.
Yes. Accounts over the threshold require an FBAR, specified assets require Form 8938, and UK funds and ISAs are often PFICs requiring Form 8621.
The Foreign Tax Credit and the US-UK treaty allocate taxing rights and offset tax paid in one country against the other, when claimed correctly.
Significantly. Moving from employee to partner changes the character of your income, adds capital and drawings questions, and should be planned for in advance.
No. A UK-only or US-only accountant leaves half the picture unmanaged; American lawyers need genuine cross-border advice.
Written by the Jungle Tax team. Contact: hello@jungletax.co.uk
