A UK tax resident is taxed on income from everywhere, not just from Britain. The Spanish apartment, the American brokerage account, the pension from a previous posting — all of it is within the UK net, whether or not a penny of it ever reaches a UK bank account.
Most people meet this rule the wrong way round: they assume income earned abroad, taxed abroad, and left abroad is nothing to do with HMRC. It is a reasonable-sounding assumption and it is wrong. UK tax follows residence, and residence brings worldwide income with it.
The good news is that the system is designed not to tax the same money twice, and the mechanism for that works reasonably well. The bad news is that it only works if you declare the income in the first place.
What Counts as Foreign Income
- Rent from property abroad — the most common category by a wide margin, and the one most often left off.
- Dividends and interest from overseas companies, funds and bank accounts.
- Employment income for work done abroad, including for a foreign employer.
- Overseas pensions, including those built up during an earlier posting.
- Gains on foreign assets, which follow the capital gains rules rather than the income ones.
The default treatment is the arising basis: it is taxable in the UK in the year it arises, wherever it sits. Leaving the money in a local account does not defer anything — that is the single most persistent misunderstanding in this area.
Foreign Tax Credit Relief
Where the source country has already taxed the income, you can normally claim credit for that tax against your UK bill on the same income. The result is that you pay the higher of the two effective rates in total, rather than both in full.
| Scenario | Foreign tax | UK tax before relief | Total paid |
|---|---|---|---|
| Foreign rate lower than UK | £200 | £400 | £400 — £200 abroad, £200 here |
| Foreign rate higher than UK | £600 | £400 | £600 — the excess is not refunded |
The second row is the one to plan around. Credit is capped at the UK tax on that income, so where the foreign rate is higher, the difference is a genuine cost with no UK remedy. Whether that outcome is correct depends on the treaty position — see our double taxation treaty guide for how taxing rights are allocated in the first place, and whether the source country should have charged that much at all.
Keep the foreign tax evidence at the time. Credit relief is a claim, and HMRC can ask for proof that the foreign tax was actually paid — a local assessment or withholding certificate. Obtaining these years later, in another language, from a tax authority you no longer deal with, ranges from tedious to impossible. File them as they arrive.
Overseas Property: the Most Common Case
An apartment abroad let out for part of the year generates UK-taxable profit, computed under UK rules rather than local ones. That distinction matters more than people expect: what your local accountant deducted may not be deductible here, and the UK figure has to be worked out separately.
Two further features catch owners out. Overseas property income is pooled separately from UK property income, so losses on one do not simply offset profits on the other. And the local country will almost certainly tax the rent as well, because under essentially every treaty the country where the property sits has the primary claim — credit relief then does the reconciling.
There is also a £1,000 property allowance: gross property income at or below it needs no return at all, and above it you can deduct the £1,000 instead of actual expenses if that produces a better answer.
The Exchange Rate Trap
Everything must be reported in sterling, converted at an appropriate rate. Two consequences follow that surprise almost everyone:
- Your UK tax bill on a fixed foreign income moves with the exchange rate. Rent unchanged in euros can produce materially more taxable sterling income than the year before.
- Currency movements can create taxable gains in their own right in some circumstances, quite separately from the underlying asset.
Use a consistent, defensible basis for conversion and keep a record of it. Switching methods between years to whichever gives the lower answer is exactly the pattern that attracts attention.
HMRC Almost Certainly Already Knows
This is worth stating plainly because it changes the risk calculation. Tax authorities exchange financial account information automatically across a very wide network of countries. A UK-resident individual holding an account abroad should assume HMRC receives data about it.
The practical implication is that non-declaration is not a quiet option any more. If you have foreign income that has not been declared, the correct response is to regularise it deliberately — disclosure routes exist and produce far better outcomes than being contacted first.
People Newly Arriving in the UK
The rules above describe the standard position for someone settled here. People who have recently become UK resident may fall under specific arrangements for foreign income and gains in their early years — HMRC's guidance on residence and the foreign income and gains regime sets out the detail, and it is one of the areas where getting advice in the first year pays for itself many times over.
If you have arrived recently, or are returning after a long absence, our moving back to the UK guide covers the year of arrival and how split-year treatment interacts with it.
Frequently Asked Questions
Do I pay UK tax on income earned abroad?
If you are UK tax resident, yes — UK residents are taxed on worldwide income under the arising basis. It is taxable in the year it arises regardless of whether the money is brought to the UK.
Do I have to declare foreign income if it was already taxed abroad?
Yes. You declare it and claim foreign tax credit relief for the tax already paid. Prior taxation abroad reduces the UK bill; it does not remove the obligation to report.
How does foreign tax credit relief work?
The foreign tax paid is credited against your UK tax on the same income, capped at the UK amount. If the foreign rate was higher, the excess is not refunded — you effectively pay the higher of the two rates.
How is rental income from an overseas property taxed?
The profit is computed under UK rules and taxed here, with credit for local tax paid. Overseas property is pooled separately from UK property, and a £1,000 property allowance applies.
What exchange rate should I use?
An appropriate rate applied consistently, with a record of the basis you used. Because everything is reported in sterling, your UK bill on an unchanged foreign income can move purely from currency shifts.
Will HMRC find out about my overseas account?
Assume so. Financial account information is exchanged automatically between tax authorities across a wide network of countries, so undeclared foreign income is far more visible than it once was.
Related Guides
Keep reading with these related guides:
- Double Taxation Treaty Relief — who has the right to tax it first
- Moving Back to the UK — the year you re-enter the worldwide net
- Payments on Account — how the resulting bill is collected
- How to Become Non-Resident — the test that decides whether any of this applies
- Non-Resident Landlord Tax — the mirror image, for UK property owned from abroad
- Country Tax Comparisons — local rates in the source country
- All Tax Guides
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