The US-Portugal income tax treaty

By Brent Chudoba, editor Updated September 15, 2026

Under the US-Portugal income tax treaty, the most the paying country can withhold from an ordinary investor is 15% on dividends, 10% on interest and 10% on royalties. Some recipients and some kinds of payment get a different rate, and the table below lists each one. Without a treaty, US-source dividends and royalties paid to a nonresident are withheld at 30%, while the tax code already exempts most portfolio and bank-deposit interest whether or not a treaty applies.

The treaty has generally applied since 1996. It also decides residency when both countries claim you, and assigns who taxes pensions and Social Security. It does not generally stop the US taxing its own citizens.

What are the US-Portugal treaty withholding rates?

US-Portugal treaty withholding rates and who qualifies
Income	Rate cap	Who gets this rate, and where the treaty says so
Dividends	15%	Anyone not in a category below, including an ordinary individual investor (Article 10(2))
Dividends	at least 5%	a company resident in the other country that has directly owned at least 25% of the paying company's capital for an unbroken 2 years before the dividend. The cap is whatever rate Portugal may apply to such dividends paid to European Union residents, and it never drops below 5%. It limits withholding by both countries, not only by Portugal (Article 10(3)(b))
Interest	10%	Anyone not in a category below, including an ordinary individual investor (Article 11(2))
Interest	0%	interest paid by the government of the country where it arises, or by one of its political or administrative subdivisions or local authorities (Article 11(3)(a))
Interest	0%	interest paid to the government of the other country, one of its subdivisions or local authorities, or an institution or organization (including a financial institution) wholly owned by them (Article 11(3)(b))
Interest	0%	interest on a loan of 5 years or more made by a bank or other financial institution resident in the other country (Article 11(3)(c))
Interest	15%	interest figured by reference to the profits of the issuer or a related enterprise (contingent interest), which is capped at the Article 10(2) dividend rate instead of 10% (Article 11(4))
Royalties	10%	Anyone not in a category below, including an ordinary individual investor (Article 13(2))
Royalties	0%	royalties for the use of, or right to use, containers in international traffic, which only the recipient's country of residence may tax (the Technical Explanation says this includes related equipment such as cranes and trailers) (Protocol paragraph 11)

The cap applies to income paid from one country to a resident of the other, and each treaty conditions it on that resident being the real recipient rather than a conduit; the article cited beside each rate is the one that sets the condition. Which document sets each rate today: dividends, 1994 Convention; the same-day Protocol does not change dividend rates, and no later protocol exists; interest, 1994 Convention, with Protocol paragraph 9; no later protocol; royalties, 1994 Convention, with Protocol paragraph 11; no later protocol.

What else changes the rate?

These are edge cases. If you hold ordinary shares, bonds or a copyright, skip to the next section.

Dividends: The corporate tier is not a number written into the treaty. For dividends paid after 1999, Article 10(3)(b) sets the cap at whatever rate Portugal may apply to such dividends paid to EU residents, with 5% as the minimum. The Technical Explanation says that cap applies to each country's withholding, so it also limits US tax on dividends a US subsidiary pays its Portuguese parent. The 5% shown here is that floor, and it is the figure IRS Table 1 lists. If Portugal's rate for EU parent companies were ever higher, the cap would follow it. For this tier, 'capital' means voting power when the payer is a US company, and nominal paid-in share capital when the payer is a Portuguese company (Technical Explanation). The corporate tier never applies to dividends from a US regulated investment company (RIC) or real estate investment trust (REIT), under Article 10(4). RIC dividends get 15%. REIT dividends get 15% only when the owner is an individual holding less than 25% of the REIT, and otherwise US domestic law applies. Portugal's separate substitute gift and inheritance tax on certain dividends sits outside the treaty. Protocol paragraph 8 only stops any later increase in its rate from applying to US residents.

Interest: US tax on an excess inclusion from a residual interest in a real estate mortgage investment conduit (REMIC) gets neither the 10% cap nor the exemptions and is taxed at the US domestic rate (Protocol paragraph 9). That rule applies only to US tax; otherwise the article works the same in both directions.

Royalties: The 10% cap covers every kind of royalty in Article 13(3), including rent for industrial, commercial or scientific equipment and payments for related technical assistance performed in the paying country. Container rental counts as a royalty under this treaty (Technical Explanation, Article 8 discussion), which is why its exemption sits here.

Which country are you a resident of under the US-Portugal treaty?

If the US and Portugal both treat you as a resident under their own laws, Article 4(2) decides. It works through these tests in order, and stops at the first one that points to a single country:

Where you have a permanent home available to you
If you have a permanent home available to you in both countries, where your personal and economic ties are closer (your center of vital interests)
If that center cannot be determined, or you have no permanent home in either country, where you have a habitual abode
If you have a habitual abode in both countries or in neither, the country you are a national of
If you are a national of both countries or of neither, the two tax authorities settle it by mutual agreement

Using the tie-breaker to be treated as a resident of Portugal has US consequences: you file Form 1040-NR with Form 8833 attached, and a green card holder of 8 of the last 15 years who makes the claim is treated as having ended US residency. The details are on the hub page.

How does the US-Portugal treaty tax pensions and Social Security?

Pensions (Article 20(1)(a)). A private pension for past employment is taxable only in the country where you live, and so is an annuity under 20(2). The saving clause still lets the United States tax its own citizens and residents on it. For a US citizen living in Portugal, Article 25(2) is what relieves the double tax. Government-service pensions work differently. Under Article 21(2) they are taxable only by the country that pays them, unless you are both a resident and a national of the other country. The saving clause preserves that rule only for people who are neither citizens of, nor hold immigrant status in, the country doing the taxing.

Social Security (Article 20(1)(b)). Social security and other public pensions paid by one country to a resident of the other country, or to a US citizen, may be taxed by the country paying them. That is not an exclusive right, unlike the private pension rule. The Technical Explanation says both countries may tax the payment, and the country where you live gives relief under Article 25.

Does the treaty stop the US taxing its own citizens?

Generally no. The saving clause (Protocol paragraph 1(b)) keeps that right. Each country may tax its own residents as if the treaty did not exist, and the United States may tax its citizens the same way. For this purpose a former citizen who gave up citizenship mainly to avoid tax still counts as a citizen, for 10 years after the loss.

The exceptions: Some benefits survive the saving clause, and Protocol paragraph 1(c) lists them. Everyone keeps Articles 9(2) (corresponding adjustments), 20(1)(b) (social security and public pensions), 20(4) (child support), 25 (double tax relief), 26 (non-discrimination) and 27 (mutual agreement). A second group is kept only by people who are neither citizens of, nor hold immigrant status in, the country doing the taxing: Articles 21 (government service), 22 (teachers and researchers), 23 (students and trainees) and 29 (diplomats).

What does the treaty say about students?

Article 23. A student, professional trainee or grant-funded researcher who is temporarily in the other country is exempt there for up to 5 years on three things: money from abroad for maintenance and study, the grant itself, and up to 5,000 US dollars a year of work income. A separate rule covers someone who visits as an employee or contractor of a home-country business to gain experience or study. That person is exempt for 12 consecutive months on up to 8,000 US dollars of work income. Neither rule covers research done mainly for private benefit. A US citizen or green card holder cannot use this article against US tax.

What do people most often get wrong about this treaty?

The mistake Americans retiring to Portugal most often make is reading Article 20 as an exemption. Under 20(1)(a) Portugal alone may tax a private pension, but the saving clause keeps US tax on US citizens. Relief comes through Article 25(2), which treats that income as arising in Portugal so that the double tax can be relieved. It is relief, not an exemption.

US government pensions are not a clean exception either. The Technical Explanation says the United States alone taxes a US national retired in Portugal under Article 21(2). But the saving clause lets Portugal tax its own residents on Article 21 income unless they are neither Portuguese citizens nor hold immigrant status in Portugal, and the treaty never defines immigrant status.

The corporate dividend rate is not simply 5%. It needs a direct holding of at least 25% of the payer's capital for 2 years, and the cap tracks the rate Portugal may apply to EU parent companies, with 5% as the floor.

Portugal treats a US citizen or green card holder as a US resident only if that person has a substantial presence in the United States, or has ties that would make that person a resident of the United States and not of a third country (Protocol paragraph 3(c)).

Anyone entitled to income tax benefits under the Madeira or Santa Maria Island tax-free zone rules gets no benefits from this treaty at all (Article 17(6)).

The treaty does not say how the United States treats Portuguese social security received by its own citizens or residents, and this page does not state it.

How do you claim the treaty rate?

Give the US payer Form W-8BEN naming Portugal as your country of residence, before the payment. Many countries ask a US resident for Form 6166, a US residency certificate requested on Form 8802, before they apply the lower rate on their side. Both, with the fees and who can get them, are covered on US tax treaties by country.

Sources

Every rate and article on this page was read in the treaty text and its protocols, then checked a second time by a separate review of the same documents, on September 15, 2026.