What a double taxation treaty does
A double taxation treaty, also called a double tax agreement, a double tax treaty or a tax convention, is a contract between 2 countries about income that touches both. Most follow the OECD Model Tax Convention, so the same articles turn up in most treaties, though the numbering can shift: US treaties, built on the US Model, put salaries in Article 14 rather than 15 and pensions in Article 17 rather than 18 (US Treasury, 2016 US Model), as the US-UK treaty does. Rates and wording are negotiated pair by pair.
A treaty sits on top of each country's own law and limits it: each country taxes under its own rules first, and the treaty decides whose rules give way. Claiming it is one of the legal ways to pay less tax that needs no new structure, only proof of where you live.
Who may tax which income under the OECD Model (each real treaty sets its own rates)
| Income | Article | Where it can be taxed | Limit on the country where it arises |
|---|---|---|---|
| Rent and gains from real estate | 6, 13 | Where the property is, and your country of residence with relief | No limit |
| Freelance and business profits | 7 | Your country of residence only | Only profits of a permanent establishment there |
| Dividends | 10 | Both countries | 15%, or 5% for a company holding 25% for 365 days |
| Interest | 11 | Both countries | 10% |
| Royalties | 12 | Your country of residence only | 0% |
| Gains on shares and other assets | 13 | Your country of residence only, except shares drawing over 50% of their value from real estate in the other country | 0% on the rest |
| Salaries | 15 | Where the work is done, and your country of residence with relief | 0% if the 183-day exception applies |
| Private pensions | 18 | Your country of residence only | 0% |
| Other income | 21 | Your country of residence only | 0% |
Who can use a tax treaty
Treaties protect residents of the 2 countries that signed them. Under Article 4 of the OECD Model, you are resident of a country for the treaty when its law makes you liable to tax there because of domicile, residence or a similar test, and someone taxed there only on income from local sources does not count.
Living in a territorial tax country does not shut you out. The OECD's commentary on Article 4 (paragraph 8.3 of the condensed Model) says that exclusion targets people without full liability to tax and was never meant to exclude residents of countries that tax on a territorial principle.
Being resident nowhere does shut you out, which is why a digital nomad tax plan that holds up starts by choosing a country that taxes you as a resident and has treaties with the places your income comes from.
Resident nowhere, treaty nowhere
If you travel so that no country taxes you as a resident, you have no country to name on a W-8BEN, no certificate of residence to show a payer, and no tie-breaker to argue when your old country says you never left. The payer withholds its full domestic rate, and the old country keeps its claim on your worldwide income.
A treaty rarely lowers a US citizen's US tax. Most US tax treaties have a saving clause that lets each country tax its own citizens as if the treaty did not exist, with a short list of exceptions, the IRS explains. Americans abroad use the treaty to limit the other country's tax and the US foreign tax credit for the rest.
Tie-breaker rules when 2 countries claim you: Article 4
You can be resident in 2 countries at once under their own laws, most often in the year you move. Article 4(2) then picks 1 of them with a fixed ladder: a permanent home available to you, then your center of vital interests, then your habitual abode, then nationality, and finally agreement between the 2 tax authorities (OECD Model, Article 4).
A treaty tie-breaker usually turns on the first 2 rungs: whether you kept a home available in the old country, and where your center of vital interests lies. The OECD commentary on Article 4 (paragraph 15 of the condensed Model) weighs your family and social relations, occupation, political, cultural or other activities, place of business and the place you manage your property from, taken together.
Companies follow a different rule. Under the 2017 Model, the tax authorities settle a dual-resident company's residence by agreement, having regard to its place of effective management and where it was incorporated, and until they agree it gets no treaty relief except as they allow (OECD Model, Article 4(3)). Many treaties signed before 2017 still use the older rule: the company is resident only where its place of effective management is (commentary on Article 4, paragraph 24.5).
Freelance and business profits: Articles 5 and 7
Fees you invoice as a freelancer, and the profits of your own company, fall under Article 7. They are taxable only in the country where the business is resident, unless it carries on business in the other country through a permanent establishment there, and then that country may tax only the profits attributable to it (OECD Model, Article 7).
Freelancers once had their own article. The OECD deleted Article 14 on independent personal services from its Model on April 29, 2000, moving professional income under Article 7 as business profits, according to the commentary on Article 14 in the condensed Model. Older treaties, and those built on the UN Model, still carry an Article 14.
A permanent establishment is a fixed place of business through which the business is carried on, such as an office, a branch or a place of management, and a person who habitually concludes contracts for you in that country can create one without any office (OECD Model, Article 5).
So under a treaty that follows the OECD Model, a client's country cannot tax your fees just because the client sits there, but a country you work from for months, at a desk you keep returning to, can claim the profit earned there.
Treaties built on the UN Model Double Taxation Convention can differ. Its Article 14 lets the country where you work tax professional fees once you stay 183 days in any 12-month period, even without a fixed base, and its Article 12A, added in 2017, lets the client's country tax fees for technical, managerial or consultancy services at a negotiated rate, even with no permanent establishment there.
Dividends, interest and royalties: Articles 10 to 12
Investment income is where a treaty saves cash directly, because the country where the payer sits withholds tax before the money reaches you. Without a treaty, the US takes a flat 30% from most US-source income paid to foreign persons (IRS).
The OECD Model caps the source country at 15% on dividends, or 5% for a company that holds at least 25% of the payer throughout a 365-day period, at 10% on interest, and leaves royalties to the country of residence alone (OECD Model, Articles 10 to 12).
Each pair of countries negotiates its own numbers, so the cap on dividend withholding tax in a real treaty can sit above or below the model's, and the treaty text, not the model, sets what you can claim.
The treaty rate is a ceiling the payer applies only if you document your residence in time, and skipping the claim costs you at home too: a US resident, for one, can credit only the reduced foreign tax the treaty allows, and the excess can only be reclaimed from the foreign country (IRS).
| Dividend paid | $10,000 |
|---|---|
| Withheld at the 30% domestic rateNo treaty claim on file | $3,000 |
| Withheld at a 15% treaty rateTreaty claimed on Form W-8BEN before the payment | $1,500 |
| Cash you keep without the claim | $7,000 |
| Cash you keep with the claim | $8,500 |
| Kept by filing 1 form on time | $1,500 |
Assumes a treaty with the OECD Model's cap on portfolio dividends.
Capital gains, pensions and other income
Under Article 13 of the OECD Model, gains on real estate can be taxed where the property is, and so can gains on shares that drew more than 50% of their value from that country's real estate at any time in the 365 days before the sale. Gains on other property, ordinary shares included, are taxable only where the seller lives.
Private pensions for past employment, and income no other article covers, are also taxable only in the country of residence (OECD Model, Articles 18 and 21).
So the date of a large sale matters: under a treaty that follows the model, a gain on ordinary shares realized after you become resident elsewhere is your new country's to tax, which is why some countries charge an exit tax on departure before you go.
Salaries and the 183-day rule: Article 15
Salaries are taxable where the work is physically done. The treaty exception keeps pay for work done in the other country taxable only in your country of residence when 3 conditions all hold: you are there no more than 183 days in any 12-month period starting or ending in the tax year, your employer is not resident there, and no permanent establishment of the employer there bears the pay (OECD Model, Article 15).
It decides where a salary is taxed, not where you are resident, which makes it a different test from the 183-day rule countries use for residence in their own law.
How your home country removes the double tax: Article 23
Whatever the source country may still tax, your country of residence relieves it in 1 of 2 ways. Under the exemption method (Article 23 A) it exempts the income, though it may count it when setting the rate on your other income; under the credit method (Article 23 B) it taxes the income and deducts the foreign tax, capped at its own tax on that income (OECD Model, Article 23).
The method decides the bill. With a credit you pay at least your home country's tax on the foreign income; with an exemption you pay mostly what the source country took, so the gap between a foreign tax credit and an exemption is widest when you move between a low-tax and a high-tax country.
Residents taxed on a remittance basis can lose part of the source country's relief instead: some treaties cut source-country tax only on the income remitted to the residence country, so income left abroad pays the source country's full rate, as HMRC's international manual explains for UK treaties.
How to claim tax treaty benefits
Relief reaches you in 2 ways: the payer withholds at the treaty rate, or the source country refunds the difference later. Both need proof of residence. Some source countries accept the payer's own form, signed by you. The US applies treaty rates on a Form W-8BEN that you give the payer, not the IRS, naming your treaty country in Part II with no certificate attached, and a form signed in 2026 generally stays valid until December 31, 2029 (IRS instructions for Form W-8BEN). Others want a tax residency certificate from the tax office where you live.
A US resident who needs one gets Form 6166 by filing Form 8802, and since October 1, 2026 the user fee is $105 for individuals and $230 for businesses (IRS).
Where the full rate was already withheld, the remedy is a refund claim in the source country. In the US a nonresident files Form 1040-NR with the Form 1042-S that shows the tax withheld (IRS instructions for Form 1040-NR), and the IRS allows up to 6 months to issue a refund of tax withheld at source (IRS, Publication 519).
Claiming a treaty rate on cross-border income
- Confirm you are resident in 1 of the 2 countries, and run the tie-breaker if both claim you.
- Find the treaty between your country of residence and the income's source country, its protocols, and the article and rate for your type of income.
- Check the anti-abuse article: usually a principal purpose test, or a limitation on benefits article in US treaties.
- Get a certificate of residence for the year from your own tax office, if the source country asks for one.
- Give the payer its form, such as a W-8BEN for US income, before the first payment.
- Claim the credit or exemption at home, or a refund in the source country if too much was withheld.
How to find the tax treaty between 2 countries
Start at either country's tax authority. The IRS keeps an A to Z list of US income tax treaties with the texts and technical explanations, and HMRC publishes every UK treaty by country in its tax treaties collection.
The IRS list also shows where Americans get no treaty at all: there is no entry for the United Arab Emirates, Brazil, Panama, Hong Kong or Singapore. The treaties with Russia and Belarus are marked partially suspended, and the one with Hungary terminated.
Read the treaty with its protocols, then check the multilateral instrument. The OECD's BEPS MLI covers 107 jurisdictions and over 2,000 bilateral treaties and has already modified over 1,600 of them; it is the main route by which the minimum standard against treaty abuse reaches older treaties (OECD, April 2026).
That standard can be met with the principal purpose test alone: a treaty benefit is denied when obtaining it was a principal purpose of the arrangement, unless granting it fits the treaty's purpose (OECD Model, Article 29). It limits any flag theory plan built on a company with no business reason to be where it is.
The principal purpose test: a real move and a conduit company
Treaty rate applies
You move to Portugal on a 2-year lease, live and work there, and hold foreign shares in your own name. The treaty rate on your dividends follows from where you actually live.
Treaty rate denied
You stay in a country with no treaty with the payer's country and route the dividends through a company in a well-treatied country, with no office, staff or decisions there. Getting the treaty rate was a principal purpose of that company, so the source country can refuse it and withhold its full domestic rate.
US treaties sit outside the MLI: the US is not on the OECD's list of signatories (status as of September 15, 2026), and its treaties use a limitation on benefits article instead, Article 22 of the 2016 US Model.
David's note
Before I compare headline rates, I check the treaty list. Move to the UAE, Singapore or Hong Kong with US shares and your US dividends lose 30% at source (IRS), because the US has no income tax treaty with any of them, and with no tax at home to credit it against, that 30% is the final cost. A country whose treaty halves that rate and that taxes dividends modestly can leave an investor more in hand than a tax-free country with no treaty.
