Double Tax Treaty Estimator
Tell us your residence, where you do the work and what kind of income you receive. You get an estimate of which country has primary taxing rights and the treaty caps that usually apply — the real answer depends on your residence status and on the exact article of the treaty concerned.
Estimate treaty allocation
Estimate — not a determinationTreaty relief hangs off residence — use the UK residency tool first if you are unsure.
Country where the work is performed or the income is sourced.
The treaty article that governs allocation.
Employment conditions (Article 15 / 183-day rule)
All three must be true for residence-only taxation. If any is false, the work country also gets to tax.
Country by country
How we worked it out
| Country / treaty | Dividends — Art 10 standard / qualifying | Interest — Art 11 | Royalties — Art 12 | Construction PE — Art 5 |
|---|
Qualifying = a substantial corporate holding (often ≥10% of capital, ≥25% in some treaties), usually with holding-period conditions. Construction PE = the site duration after which a building or installation project becomes a permanent establishment under Article 5. Portugal reflects the 2025 UK–Portugal Convention as recorded by this tool; that too is undated in our source data.
The UK side of the sum — 2026/27A treaty allocates taxing rights; it does not set the UK rate. These are the UK figures that decide how much tax you actually pay, and how large a foreign tax credit the UK can give.
| Income type (article) | UK treatment, 2026/27 | UK rate capping your credit |
|---|---|---|
| Employment — Art 15 | Personal allowance £12,570, then 20% on the first £37,700 of taxable income, 40% to £125,140 and 45% above. Employee NIC 8% from £12,570 to £50,270, then 2%. | 20 / 40 / 45% |
| Business profits — Art 7 | Through a company: corporation tax 19% on augmented profits up to £50,000, 25% over £250,000, marginal relief between the two (26.5% effective). As a sole trader: 20 / 40 / 45% plus Class 4 NIC at 6% to £50,270 and 2% above. | 19–25% or 20 / 40 / 45% |
| Dividends — Art 10 | £500 dividend allowance — a nil-rate band that uses up basic-rate band, not a deduction — then 10.75%, 35.75% or 39.35%. Both the ordinary and upper rates rose 2 percentage points on 6 April 2026. | 10.75 / 35.75 / 39.35% |
| Interest — Art 11 | Personal savings allowance £1,000 (basic rate), £500 (higher) or £0 (additional), plus a 0% starting rate on up to £5,000 of savings income; the rest at 20 / 40 / 45%. | 20 / 40 / 45% |
| Royalties — Art 12 | Taxed as trading or property income at 20 / 40 / 45%, or as part of company profits at 19–25%. | 20 / 40 / 45% |
| Pension — Art 18 | Taxed as income at 20 / 40 / 45% after the £12,570 personal allowance. The tax-free lump sum allowance is £268,275. | 20 / 40 / 45% |
Scottish taxpayers: employment, self-employment and pension income is taxed on the Scottish bands (19% to £16,537, 20% to £29,526, 21% to £43,662, 42% to £75,000, 45% to £125,140, 48% above), while dividends and savings are reserved and follow the UK-wide rates. National Insurance is not devolved — and it is not a treaty tax either, so social security follows the relevant agreement (A1 or certificate of coverage) rather than Article 15.
Frequently asked questionsA bilateral agreement between two countries that allocates taxing rights to avoid the same income being taxed twice. The UK has treaties with around 130 countries, most based on the OECD Model Convention with bespoke variations on withholding caps and tiebreaker rules. The treaty decides which country may tax; each country's own law decides how much.
Under Article 15 of most UK treaties, employment income from working in another country is taxed only in your country of residence if you spend fewer than 183 days there, your employer is not resident there, and the cost is not borne by a permanent establishment there. All three conditions must be met — fail any one and the host country can also tax. Note: many treaties use a rolling 12-month period rather than the host's tax year.
A fixed place of business through which the business of an enterprise is wholly or partly carried on. For contractors, PE risk arises from long site-based assignments (typically 6–12 months depending on treaty), having a UK office abroad, or local agents with authority to conclude contracts. PE triggers full local corporate and personal tax exposure and is one of the largest hidden risks in overseas contracting.
For the 183-day rule, "employer" isn't always the formal legal employer. Many tax authorities apply an "economic employer" test — who really bears the cost, directs the work and benefits from it. If your formal UK employer recharges your salary to the overseas client, the overseas client may be treated as your employer for treaty purposes and the 183-day rule fails.
If you are taxed on the same income in both the UK and an overseas country, the UK generally gives you credit for the foreign tax paid, up to the UK tax due on that income. You claim FTC on the SA106 supplementary pages of Self Assessment. The cap matters: on a dividend taxed at the UK ordinary rate of 10.75% in 2026/27, a 15% foreign withholding is only creditable to 10.75% — the rest is a real cost unless you can reclaim it from the source country.
The UK has treaties with around 130 countries. The 20 in the dropdown cover the most common contractor destinations. For others, treaties are generally based on the OECD Model with similar 183-day, PE and withholding logic but country-specific caps. The HMRC tax treaties register lists every active treaty.
No. Treaty interpretation depends heavily on facts and circumstances, MLI modifications since 2017, and the specific text of each treaty. This estimator gives a directional answer based on simplified OECD principles and the standard withholding caps in its own table. Always confirm with a qualified international tax adviser before signing or filing.
About this estimator
Most UK double tax treaties follow the OECD Model Convention with country-specific variations. This tool applies the standard OECD rules for the most common articles a contractor will encounter:
Article 7 (Business profits) — taxed in the country of residence unless the contractor has a permanent establishment in the other country. PE creates a tax presence even without local incorporation.
Article 10–12 (Dividends, interest, royalties) — primary right to source country up to a treaty cap, with foreign tax credit available in the residence country to relieve double tax.
Article 15 (Employment income) — taxed in the residence country unless work is performed in the other country, in which case the so-called 183-day rule allocates rights based on three cumulative conditions.
Article 18 (Private pensions) — generally taxed only in the country of residence. Government service pensions follow Article 19 and are usually taxed by the paying state.
The UK figures used alongside those articles — personal allowance, income tax bands, dividend rates, corporation tax and National Insurance — are the published rates for the 2026/27 tax year and financial year 2026. The treaty caps are not: they are this tool's own table, undated in our source data and reviewed in July 2026. Multilateral Instrument (MLI) modifications, principal-purpose tests, beneficial-ownership requirements and treaty-shopping protections may affect availability of benefits in practice — and reduced rates usually require a Certificate of Residence. Always confirm with a qualified adviser before claiming a treaty rate at source.
This estimator is an indicative guide to how UK double tax treaties allocate taxing rights between countries. It is not a formal determination and must not be relied on as professional tax advice. Treaty relief depends on your residence status and on the specific article that applies.
The treaty caps it shows are the tool's own table of standard UK rates, reviewed July 2026 and carrying no source or date of their own (Portugal reflects what the tool records as the 2025 UK–Portugal Convention). It does not model MLI principal-purpose tests, beneficial-ownership or limitation-on-benefits conditions, certificate-of-residence formalities, the "economic employer" concept, service or agency permanent establishments, or the many factual nuances a tax authority will weigh in a real review.
Before claiming a treaty rate at source or filing a return, get qualified advice from a chartered international tax adviser or contractor accountant. ContractorUK is not a tax adviser and accepts no liability for decisions made based on this tool.
This tool is an estimate, not a determination of treaty entitlement. UK rates are taken from the published 2026/27 figures; check the treaty itself in the HMRC tax treaties collection and the guidance on tax on foreign income, or ask a qualified adviser.