Taxes When Working Abroad: Residence, Income and Double-Tax Treaties
Where you are allowed to live, where you work, and where you are tax-resident can be three different answers. A visa or a residence permit is immigration status. Tax residence is a test set by a tax authority. This article does not say where any reader owes tax. It does not list tax rates.
The worked example is the United Kingdom, from HMRC’s Statutory Residence Test notes, updated 11 June 2026, and from GOV.UK’s page on UK residence and tax, both checked on 25 September 2026. A second country is not added.
UK tax residence is several tests
The Statutory Residence Test took effect on 6 April 2013. Each UK tax year, 6 April to 5 April, is looked at on its own. Spending 183 days in the UK is one automatic UK test. HMRC’s notes say that if you have been in the UK for 183 or more days you will be UK resident, and there is no need to consider any other tests. That sentence is not a rule that fewer than 183 days makes you non-resident. Other automatic UK tests exist, including a home test and a full-time work in the UK test. If no automatic test settles the year, a sufficient ties test looks at days together with connections such as family, accommodation, and work. How many ties are required depends on whether you were UK resident in any of the three previous tax years. The tables are in the HMRC notes. They are not reproduced here as a calculator.
Automatic overseas tests can make you non-resident, and they have their own conditions. You meet the first if you were UK resident in one or more of the three previous tax years and you spend fewer than 16 days in the UK. You meet the second if you were UK resident in none of those three years and you spend fewer than 46 days in the UK. A third test is full-time work overseas, with a limit of fewer than 91 days in the UK and fewer than 31 days on which you work more than three hours in the UK, and with no significant break from the overseas work. Sixteen days and 46 days are not interchangeable, and neither is a worldwide day count.
The day count itself can change. HMRC says it may be reduced for days spent in the UK because of exceptional circumstances, and it may be increased under a deeming rule. The notes point to further HMRC pages for those adjustments.
What residence does to UK tax
GOV.UK’s residence page says non-residents pay UK tax on their UK income and do not pay UK tax on their foreign income. Residents normally pay UK tax on all their income, whether it is from the UK or abroad. Employment income can still be taxed where the work is done and where the employer is, as well as where you are resident. Tax taken from payroll is not the final answer to which country has the right to tax.
When you move, the tax year is not automatically cut in two. Split-year treatment can divide a year in which you are UK resident into a UK part and an overseas part, and only if the conditions for a case are met. GOV.UK says you will not get it if you live abroad for less than a full tax year before returning, and that other conditions also apply. Each case has its own conditions in the HMRC notes.
A double-tax treaty allocates rights
Two countries can both have a claim on the same income. A double-tax treaty between them may say which country taxes a type of income, and it may provide a credit or an exemption so that the same income is not fully taxed twice. Whether that happens depends on the treaty and on the facts. A treaty does not make foreign income tax-free, and it is not a promise that you will never pay tax in more than one country. No treaty article is quoted here. Use the tax authority’s own treaty text for the two countries involved.
Social security is a separate charge
Social-security or national-insurance contributions are not income tax. A move can leave you paying contributions in the country where you work even when income tax is handled under a different rule. An agreement that coordinates contributions between two countries is its own instrument. None is explained here.
A year that crosses a border can need a qualified tax adviser. This article does not recommend a firm. Status, rates, and treaty texts can change. Check the current HMRC guidance, or the tax authority of the other country, before you file.
Sources
- HMRC via GOV.UK: RDR3, Statutory Residence Test notes, updated 11 June 2026
- GOV.UK: Tax on foreign income, UK residence and tax
