You earn rent, dividends or a salary in one country and file a tax return in another. Working out how to avoid double taxation then looks like a formality, something the two tax offices will settle between them. They rarely do.
Double taxation arises when two States tax the same income in the hands of the same person, usually because one taxes you as a resident and the other taxes the income at its source. The term also covers company profits taxed in the company, then again as dividends in the shareholder's hands. For cross-border income, relief usually exists. It has to be chosen, claimed and evidenced, and that part falls to you.
Usually not, but with an ordinary credit you will not pay the lower rate either. Relief normally exists, under a treaty or under domestic law. What it removes is the second layer of tax.
Relief stops two States charging you in full on the same income; it does not let you pick the cheaper of the two.
Where the foreign rate is higher, that rate is the final one you pay. Where it is lower, a credit limits your home tax to the difference between the two rates.
Relief is not automatic: it depends on a method, a claim and a deadline, in that order.
Start with the treaty, if there is one. Its elimination article fixes which method your State of residence applies; UK treaties, for instance, give relief by credit. Without a treaty, domestic law decides.
According to the OECD's Model Tax Convention commentary (2017), “the exemption methods look at income, while the credit methods look at tax”.
Full exemption ignores the foreign income. Exemption with progression leaves it untaxed but counts it to set the rate on the rest. Under the OECD's exemption article, dividends and interest still receive a credit instead.
A full credit offsets all the foreign tax. An ordinary credit stops at a ceiling, the home tax attributable to that income. The UK measures it item by item (tax with the item minus tax without it), the US as a proportion of total tax, by income category.
In the IRS's words, “A credit reduces your actual U.S. income tax on a dollar-for-dollar basis, while a deduction reduces only your income subject to tax.” In the UK, it is generally preferable only where no tax is due that year, for example because of losses.
| Method | What the State of residence does | What limits it | Who tends to benefit |
|---|---|---|---|
| Exemption | Leaves the income out of the tax base | Progression can raise the rate on other income | Investors taxed lightly at source |
| Credit | Sets foreign tax against home tax | A ceiling: home tax on that income | Investors taxed abroad at or below the home rate |
| Deduction | Treats foreign tax as an expense | Relieves only part of the foreign tax | Investors with no home tax due that year |
Exemption takes the foreign income out of the tax base. A credit offsets the foreign tax against the home tax, up to a ceiling. A deduction treats the foreign tax as a cost. A treaty, where there is one, fixes which method applies.
Take an investor resident in State R, with 150,000 of income there and 50,000 of net rent from State S (illustrative figures, generic currency). State R taxes 20% up to 50,000, 35% up to 150,000 and 45% above: 67,500 on 200,000, an average of 33.75%. State S takes 20% of the rent in case A (10,000), 40% in case B (20,000).
| Method | State R tax, case A | Total tax, case A | State R tax, case B | Total tax, case B |
|---|---|---|---|---|
| Full exemption | 45,000 | 55,000 | 45,000 | 65,000 |
| Exemption with progression (150,000 at 33.75%) | 50,625 | 60,625 | 50,625 | 70,625 |
| Ordinary credit, ceiling 16,875 (67,500 x 50,000 / 200,000) | 57,500 | 67,500 | 50,625 | 70,625 |
| Full credit | 57,500 | 67,500 | 47,500 | 67,500 |
| Deduction (foreign tax deducted from income) | 63,000 | 73,000 | 58,500 | 78,500 |
Full exemption gives the lowest total in both cases, deduction the highest. Under the ordinary credit in case A, the total equals State R's own tax on the whole income: you pay the higher of the two rates. In case B the foreign tax exceeds the ceiling, so 16,875 is credited and 3,125 becomes excess credit.
It depends on your State of residence. A UK individual cannot carry it “forwards or backwards”. According to IRS Publication 514 (2025 returns), US taxpayers get “a 1-year carryback and then a 10-year carryover”.
This example uses a proportional ceiling, as the US does. A ceiling measured on the top slice of income, as in the UK (67,500 minus 45,000 = 22,500), would credit case B's 20,000 in full.
A certificate of tax residence proves where you are resident; the tests that establish residence are a separate subject. It guarantees nothing: the overseas authority decides.
| Jurisdiction | Document | What the issuing authority states |
|---|---|---|
| United Kingdom | Certificate of residence (HMRC) | Needs UK residence and a treaty with the country concerned; refused without entitlement to treaty benefits |
| United States | Form 6166, requested with Form 8802 | USD 105 per Form 8802 for individuals (USD 85 before 1 October 2026); apply at least 45 days ahead |
| United Arab Emirates | Tax residency certificate (Federal Tax Authority) | AED 50 submission fee plus AED 1,000 for an unregistered natural person; estimated 10 business days |
Declaring foreign income is one obligation; reporting the account that receives it is another, set by offshore account reporting rules.
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Begin Your Journey With UsRelief does not need a treaty. Many cases are removed by domestic rules alone, through exemption or credit. In the UK, you usually still get unilateral relief without an agreement, unless the foreign tax does not correspond to UK Income Tax or Capital Gains Tax.
The same applies to gaps inside a treaty. HMRC's own illustration is the UK-US agreement, which covers US federal income taxes but not state taxes, where unilateral relief is available in many cases.
The UAE does not appear on the IRS list of US income tax treaties, so a US citizen resident in Dubai relies on US domestic relief. An American abroad may exclude foreign earnings instead, but cannot then credit or deduct foreign taxes paid on that income.
Relief is one line of a wider plan for anyone living across borders, the subject of cross-border financial planning for expats.
Relief not claimed correctly and on time is lost.
| Jurisdiction | What | Time limit |
|---|---|---|
| United Kingdom | Foreign Tax Credit Relief claim | Fourth anniversary of the end of the tax year, or 31 January after the tax year in which the foreign tax is paid, if later |
| United States | Choosing the credit, or switching from deduction | 10 years from the regular due date of the return for the year concerned |
| Germany | Withholding tax refund to a non-resident | Four years after the end of the calendar year of the income; extended to one year after payment of the tax, if later |
| Switzerland | Anticipatory tax refund | In principle, three years after the end of the calendar year in which the income fell due |
Then comes the wait. German refunds can take more than 20 months to process; Swiss ones can take several months, and a claim is generally accepted only once a year. More than 450 different refund forms exist across the EU. Council Directive (EU) 2025/50 creates a common digital tax residence certificate and two fast-track procedures, applicable from 1 January 2030.
The mistakes that lose relief are procedural:
Relief not claimed correctly and on time is lost. The mistakes that forfeit it are procedural: a claim made in the wrong State, a missed deadline, a special regime that gives no credit, or mixed choices in the same year.
The path is short for one income between two States with a treaty. It lengthens with several income types or source States, a residence that changes mid-year, or income held through an entity. It covers income that is or will be taxed twice, not the planning of a move. Where income arises and who holds it are decided upstream, through wealth structuring for cross-border assets.
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Three situations can leave a residual cost:
The foreign tax is deducted from the foreign income instead of being set against the tax itself. It is the UK default when no credit is claimed, and a yearly choice in the US.
Typically when your case involves:
A treaty relieves nothing until you claim, in the right State, often with a certificate of tax residence. In the UAE, the Federal Tax Authority issues it. Even then, the overseas authority decides whether relief is granted.
This guide is provided for general information purposes only and does not constitute tax or financial advice. Tax treatment depends on individual circumstances and on rules that change.
