US Portugal Tax Treaty: What It Does for Americans

Yes. The United States and Portugal signed a convention on taxes on income, with a related protocol, at Washington on 6 September 1994, and the IRS publishes the text. It decides which country may tax which income and gives credit for tax paid, but it contains a saving clause that lets the United States keep taxing its own citizens.

This guide goes deeper into the treaty than the short paragraph in our guide to US taxes for Americans abroad, which is the place to start for filing deadlines, the exclusion, the credit and foreign account reports. It reports what the convention text and the IRS pages say, in their words where the wording matters. It is not tax advice: a U.S. tax professional who knows expat returns should read your numbers.

What we read, and what the date of this guide refers to

We read the IRS and Treasury pages named at the end on 18 October 2026, and the full text of the convention and protocol as the IRS publishes it. The IRS pages show their own review dates: 10 January 2026 for the tax treaties overview, 14 March 2026 for the page on claiming treaty benefits, 8 August 2026 for the Portugal treaty documents page and 11 August 2026 for the Form 8833 page. The newest, 11 August 2026, is the date of the latest information in this guide. The convention itself dates from 1994 and we found no amending protocol on the IRS page, which lists only the 1994 treaty and a 1999 technical explanation. We also read the Treasury Department’s technical explanation of the convention, linked from that page, and the Form 8833 PDF with its instructions. Everything below on the articles comes from the convention text, and the technical explanation is quoted only where it is named.

Is there a tax treaty between the United States and Portugal?

Yes. The IRS page on Portugal tax treaty documents offers an income tax treaty PDF dated 1994 and a technical explanation PDF dated 1999. The Treasury Department’s treaties page lists, under Portugal, the convention and protocol “signed Sept 6, 1994”. The PDF is titled the convention between the Government of the United States of America and the Portuguese Republic for the avoidance of double taxation and the prevention of fiscal evasion with respect to taxes on income, together with a related protocol, and carries the line “General effective date under Article 30: 1 January 1996”.

Four points on scope, all from the text:

• Who it covers. Article 1 says it applies “to persons who are residents of one or both of the Contracting States”. Article 17 on limitation on benefits says a resident is entitled to the benefits only if it is, among other categories, “an individual”.
• Which taxes. Article 2 lists Portuguese personal income tax (IRS), corporate income tax (IRC) and the local surtax (Derrama), and on the U.S. side the federal income taxes imposed by the Internal Revenue Code, “excluding social security contributions”. Paragraph 2(a) of the Protocol adds that Article 2 does not apply to social security contributions established under Portuguese law. State income taxes are not on the list; the IRS overview says some states honor treaties and some do not, and tells you to ask your state tax authority.
• How long it lasts. Article 31 says it stays in force until a country ends it, which either may do at any time after 5 years from entry into force with at least 6 months of notice through diplomatic channels. We found no notice of termination on the pages we read.
• Who can use it. The IRS overview says “Tax treaties generally reduce the U.S. taxes of residents of foreign countries” and that, with certain exceptions, they “do not reduce the U.S. taxes of U.S. citizens or U.S. treaty residents”.

Does the treaty stop the IRS from taxing me?

Not if you are a U.S. citizen. That is the work of the saving clause, paragraph 1(b) of the Protocol:

“a Contracting State may tax its residents (as determined under Article 4 (Residence)), and the United States may tax its citizens, as if the Convention had not come into effect.”

The same paragraph extends “citizen” to a former citizen whose loss of citizenship had as one of its principal purposes the avoidance of tax, for 10 years after the loss. The clause cuts both ways: Portugal may also tax its own residents as if the convention did not exist. The IRS says the same thing in plain terms, that U.S. citizens and treaty residents “are subject to U.S. income tax on their worldwide income”.

Paragraph 1(c) then lists what the saving clause does not affect. The text splits it in two:

So for a U.S. citizen living in Portugal, the practical content of the treaty is mostly in the first row: the credit in Article 25, the protection against discriminatory taxation in Article 26 and the right to ask the tax authorities to settle a dispute in Article 27. The second row is for people with no U.S. status. Whether any other article helps you is a question for your adviser; the saving clause says those other articles do not limit the U.S. tax on a citizen.

Which country counts me as a resident?

Article 4 decides it for the treaty, using each country’s own law first. A resident is a person who “under the laws of that State, is liable to tax therein by reason of his domicile, residence, place of management, place of incorporation, or any other criterion of a similar nature”. If an individual is a resident of both countries, paragraph 2 applies these tests in this order:

1. The state where he has a permanent home available. If he has one in both, the state with which his personal and economic relations are closer (the “center of vital interests”).
2. If that cannot be determined, or he has no permanent home in either, the state where he has an habitual abode.
3. If he has an habitual abode in both or neither, the state of which he is a national.
4. If he is a national of both or neither, the two competent authorities settle it by mutual agreement.

The Protocol adds a rule that matters to Americans in Portugal. Paragraph 3(c) says Portugal “shall treat a United States citizen or an alien admitted to the United States for permanent residence (a ‘green card’ holder) as a resident of the United States only if he has a substantial presence in the United States, or would be a resident of the United States and not of a third country” under the tie-breaker tests in Article 4(2)(a) and (b). That is a sentence about Portugal’s treatment of you, written for the Portuguese side.

The IRS overview speaks of the same situation from the U.S. side. A person who is a resident of both countries under each country’s laws is a “dual resident taxpayer”, the treaty must contain a provision to settle the conflict, and one who “claims treaty benefits as a resident of the other country” must file Form 1040-NR and attach a fully completed Form 8833. We did not read how that rule works with the saving clause for a U.S. citizen, and we do not draw a conclusion. How Portugal itself decides residence is for our planned guide on Portuguese tax residence and the Portal das Financas, which we have not used here.

What does the treaty say about pensions and Social Security?

Article 20 is titled “Pensions, Annuities, Alimony, and Child Support”. Subject to Article 21 on government service, its first paragraph says two things:

• Paragraph 1(a): “pensions and other similar remuneration derived and beneficially owned by a resident of a Contracting State in consideration of past employment shall be taxable only in that State”.
• Paragraph 1(b): “social security benefits and other public pensions paid by a Contracting State to a resident of the other Contracting State or a citizen of the United States may be taxed in the first-mentioned State”, that is, the state that pays.

Paragraph 2 says annuities derived and beneficially owned by a resident are taxable only in that state, and defines an annuity as a stated sum paid periodically at stated times during a specific time period, under an obligation to make the payments in return for adequate and full consideration other than services. Article 21(2) says a pension paid by a country or its subdivisions for government service is taxable only in that country, unless the individual is a resident and national of the other.

Now read these together with the saving clause. Paragraph 1(c)(i) of the Protocol names “paragraphs 1(b) and 4 of Article 20” among the benefits the saving clause does not affect. It does not name paragraph 1(a) or paragraph 2. The Treasury technical explanation says of Article 20: “with the exception of paragraph 4, Article 20 is subject to the provisions of the ‘saving clause’… so that, in general, the United States may tax its citizens and residents on pensions, annuities, and alimony without regard to any restriction in Article 20.” What that means for a given IRA, a 401(k) or Social Security payment is not explained on any page we read, so we do not state it. Our guide to the retirement and passive income visa covers the immigration side; our planned guide on foreign pensions and Portuguese tax will cover the Portuguese side.

What does it say about dividends, interest and property gains?

These articles set ceilings on the tax the country where the income arises may charge a resident of the other country. They do not set the rate Portugal or the United States actually charges, which comes from domestic law we have not read in this guide.

Two cautions follow. First, these are limits on the source country’s tax, so for a U.S. citizen they sit under the saving clause: the United States can still tax the same income, and relief then comes from Article 25. Second, the text caps the tax a country may charge; it does not say what happens if more was withheld, which we have not read an official page on.

How does the treaty relieve double taxation?

Through Article 25. Paragraph 1 says that, “in accordance with the provisions and subject to the limitations of the law of the United States”, the United States shall allow to a resident or citizen of the United States, as a credit against U.S. tax on income, “the income tax paid to Portugal by or on behalf of such citizen or resident”. The same paragraph covers a U.S. company owning at least 10 percent of the voting stock of a Portuguese company that pays it dividends.

Paragraph 2 is written for people in your position:

“In the case of an individual who is a citizen of the United States and a resident of Portugal, income that may be taxed by the United States solely by reason of citizenship shall be deemed to arise in Portugal to the extent necessary to avoid double taxation, provided that the tax paid to the United States will not be less than the tax that would be paid under the Articles of this Convention if the individual were not a citizen of the United States.”

Paragraph 3 is the Portuguese side. Where a resident of Portugal receives income that the convention allows the United States to tax (other than solely by reason of citizenship), Portugal allows a deduction from its tax equal to the U.S. income tax paid, limited to the part of the Portuguese tax attributable to that income. A Portuguese company with at least 25 percent of a U.S. company held for 2 years gets a deduction for 95 percent of the dividends. Our guide on foreign earned income exclusion versus foreign tax credit, planned, will compare the credit with the exclusion; the pillar guide summarizes both.

What does it say if I work or run a business in Portugal?

Two articles matter. Article 16 on employment says salaries and wages derived by a resident of one country are taxable only in that country “unless the employment is exercised in the other Contracting State”, in which case the other country may tax them. Paragraph 2 is an exception for short stays: remuneration for work in the other country stays taxable only in the first country if the person is present there no more than 183 days in any 12-month period, the employer is not a resident of the other country and a permanent establishment there does not bear the pay. Article 15 on independent services says professional income is taxable only in the country of residence, except where there is a fixed base regularly available in the other country, or a stay of 183 days or more in any 12-month period in which case only income from activities performed there may be taxed there.

These are the treaty’s rules; the saving clause still applies to a U.S. citizen. For visas, contracts and the Portuguese rules on working, see working in Portugal as an American or a Briton.

How do I claim a treaty position on my US return?

Start with the IRS page on claiming tax treaty benefits, last reviewed 14 March 2026. Read it carefully, because it is written mainly for foreign persons who receive U.S. income, whom it calls “the payee”. For that case it says the payee gives a Form W-8BEN or Form 8233 to the payor to reduce withholding. That part is not about a U.S. citizen living in Portugal.

The part that can matter to you is headed “Exemption on the payee’s tax return”. It says:

• If the payee claims treaty benefits that override or modify any provision of the Internal Revenue Code, and by doing so the payee’s tax “is, or might be, reduced”, the payee must attach a fully completed Form 8833, Treaty-Based Return Position Disclosure Under Section 6114 or 7701(b), to the tax return.
• A payee must file a return and Form 8833 for three listed cases: a reduction or modification in the taxation of gain or loss on a U.S. real property interest, a change to the source of an item of income or a deduction, and “a credit for a specific foreign tax for which foreign tax credit would not be allowed by the Internal Revenue Code”. A payee must also file it when receiving payments totaling more than 100,000 dollars and determining country of residence under a treaty and not under the alien status rules.
• A payee does not have to file it for these situations, among others: a reduced rate of withholding on interest, dividends, rent or royalties; a treaty exemption on income from dependent personal services, pensions, annuities, social security and other public pensions, or income of artists, athletes, students, trainees or teachers; and payments or items of income that are otherwise required to be disclosed and total no more than 10,000 dollars.
• The page says the penalty for failing to report when required is 1,000 dollars for each failure.

The IRS page for the form itself says taxpayers use Form 8833 “to make the treaty-based return position disclosure required by Internal Revenue Code section 6114”, and that dual-resident taxpayers use it for the disclosure required by Regulations section 301.7701(b)-7. The instructions in the Form 8833 PDF (Rev. December 2022) list, among positions that must be reported, one that a treaty grants a credit for a foreign tax which is not allowed by the Code. Among positions for which reporting is waived, they list one that a treaty reduces or modifies the taxation of income derived by an individual from dependent personal services, pensions, annuities, social security and other public pensions. Whether your own position falls under either is a question for your preparer.

One more IRS fact is useful for the Portuguese side. The tax treaties overview says foreign tax authorities “sometimes require certification from the U.S. Government that an applicant filed an income tax return as a U.S. citizen or resident”, and points to Form 8802 and the page on Form 6166, the certification of U.S. tax residency. We did not read those pages, and we have not read what Portugal’s tax authority requires.

What if the two countries disagree?

Articles 27 and 28 give two procedures. Under Article 27 a person who considers that the actions of one or both countries result in taxation not in accordance with the convention may present the case to the competent authority of the country where he is a resident or national, “within 5 years from the first notification of the action resulting in taxation not in accordance with the provisions of this Convention”. The authority tries to resolve the case with its counterpart, and any agreement is implemented despite domestic time limits.

Article 28 provides for the exchange of information between the tax authorities. Paragraph 14 of the Protocol says the information that may be exchanged includes records of financial institutions, to the extent permitted by the domestic law of the country asked. Our bank account guide covers what the banks in Portugal ask.

Related guides on this site: Portuguese tax residence; tax on foreign pensions in Portugal; the exclusion versus the foreign tax credit; U.S. filing deadlines and extensions from abroad.

More guides on this site: IRA and 401(k) distributions and the treaty pension article.

What to take away

The treaty exists and is worth reading, but for a U.S. citizen its main job is the credit in Article 25 and the protections the saving clause leaves in place, not an exit from U.S. tax. Check three things with a professional: how Article 4 and the Protocol decide your residence, how Article 20 applies to your pension or Social Security, and whether your return needs Form 8833.

We read these pages on 18 October 2026: the IRS pages on Portugal tax treaty documents, on tax treaties, on claiming tax treaty benefits and on Form 8833; the Treasury Department treaties page; the PDF of the 1994 convention and protocol; the Treasury technical explanation; and the Form 8833 PDF. We could not read the list of conventions on the Portuguese tax authority’s site, so this guide does not use it.

For the broader picture, see moving to Portugal as an American.