What is Expatriate Tax? The UK & Non-UK citizen differences

Expatriate tax refers to the UK tax and social security obligations that arise when someone works outside their home country for an extended period, whether that’s a UK employee posted abroad, a UK business sending staff overseas, or someone from another country coming to work in the UK.

If your business has staff on long-term overseas postings, or you’re considering working overseas yourself, the tax position can often be complex. It depends on where the individual is tax resident, what the destination country’s rules require, and what obligations fall on the employer as well as the individual.

What determines expatriate tax treatment?

The starting point is always residency, not nationality or where someone is employed. A UK national can become non-UK resident for tax purposes while working abroad, just as someone of another nationality can become UK resident while working here. Residency, not citizenship, decides which country has the primary right to tax someone’s income.

As a UK resident, an individual is liable to UK income tax and Capital Gains Tax on worldwide income and gains. As a non-resident, UK tax generally only arises on certain UK-source income and gains.

Residency is established under the Statutory Residence Test, a detailed piece of UK tax legislation built around day counts, ties to the UK, and a series of automatic tests. We’ve covered the mechanics in full in our statutory residence test guide and our guide to leaving the UK to work overseas,. The point that matters for expatriate tax specifically is that residency status, not the posting itself, is what triggers the tax consequences below.

What does this mean for the individual?

If an individual remains UK resident while working abroad, they stay liable to UK tax on worldwide income and gains, with relief potentially available for tax already paid overseas under the relevant double tax treaty (where one exists).

If an individual becomes non-UK resident, UK tax generally only applies to income and gains with a UK source: profits from a UK trade or property business, employment income relating to UK duties, and certain UK investment income. Some income, including specific dividends, interest and other savings, may qualify as Disregarded Income, which is effectively tax-free for a non-resident.

Non-UK residents, including British passport holders, can generally still claim the UK personal allowance on the same basis as UK residents. For 2026/27, that allowance remains £12,570, frozen at that level since income tax thresholds were held down in successive Budgets.

Becoming non-UK resident for tax purposes doesn’t remove tax obligations altogether, it usually shifts them to the destination country. Anyone working abroad for a sustained period is likely to have personal tax compliance obligations there too, and will need to seek local advice alongside UK advice.

What does this mean for the employer?

An employer sending staff overseas, or employing someone who works partly or wholly outside the UK, has obligations of its own to manage.

This section covers the tax and social security side; for the wider employment law checklist, immigration status, data protection, IP ownership, and health and safety, see our guide to working remotely abroad.

Payroll. UK PAYE obligations don’t automatically stop when an employee starts working abroad; they depend on the employee’s residency position and, often, on agreement from HMRC to operate a modified or “NT” payroll basis once non-residence is established. Getting this wrong risks over-withholding UK tax on income that shouldn’t be taxed here, or under-withholding on income that should.
Social security. The employer usually carries the compliance burden for confirming which country’s social security scheme applies to a posted employee, including obtaining an A1 certificate of coverage for postings within the EU, EEA or Switzerland, or the equivalent under a reciprocal agreement elsewhere. Get this wrong and the business can end up liable for contributions in two countries at once.
Overseas reporting. Many destination countries require local payroll registration, tax withholding, or social security reporting for an employee working there, regardless of where they’re contractually employed. This is a local compliance question as much as a UK one, and needs advice in both jurisdictions.
Structuring the posting. Whether someone is seconded, transferred to a local entity, or dual-employed changes the tax and social security analysis substantially. This is worth deciding deliberately rather than defaulting into, and ideally before the move happens.

Getting the timing right

Whether the question is personal or employer-side, the same principle applies: expatriate tax planning works best well before the move, not after it. Residency status is determined by facts that accumulate over the tax year, so decisions about UK ties, property, and timing of departure or arrival are far easier to plan in advance than to unwind retrospectively.

If you’re looking for advice on your residency status, or that of your employees, whether moving abroad or coming to work in the UK, Price Bailey’s Tax team can advise across income tax, Capital Gains Tax and Inheritance Tax, and on the employer-side payroll and social security obligations that come with an overseas posting. Contact one of the team using the form below.

We always recommend that you seek advice from a suitably qualified adviser before taking any action. The information on this page is intended as a general guide only. While we work to keep our content accurate and up to date, we cannot guarantee that it reflects the position at the time you are reading it. No responsibility for loss occasioned by any person acting or refraining from action as a result of this material can be accepted by the authors or the firm. For more information on our editorial process, click here.

Sign up to receive exclusive business insights

Join our community of industry leaders and receive exclusive reports, early event access, and expert advice to stay ahead – all delivered straight to your inbox.