Two systems that both claim you
The United States taxes on citizenship: every US citizen and green-card holder files Form 1040 on worldwide income, wherever they live. Portugal taxes on residence: more than 183 days in a twelve-month window, or a home kept as your habitual residence (IRS Code, art. 16.º), and worldwide income is declared here too.
The treaty of 1994 does not remove the American obligation — its saving clause (protocol, paragraph 1(b)) lets the US tax its citizens “as if the Convention had not come into effect”. What the treaty does is decide which country has the first right to each kind of income, and oblige the other to give credit. Article 25(2) adds the rule that makes the system work for Americans in Portugal: income the US taxes only because of citizenship is treated as Portuguese-source, so the US credits the Portuguese tax, not the other way round.
- $132,900 foreign earned income exclusion for 2026 (Form 2555) — for salaries and self-employment, not pensions or investment income
- 15 June automatic US filing date for Americans abroad, extendable to 15 October; Portugal files 1 April – 30 June
- $10,000 aggregate balance that triggers the FBAR on Portuguese accounts
- 1 August 1989 Social Security totalization agreement: no double contributions, credits combined
Income tax, side by side
| Portugal 2026 | United States 2026 | |
|---|---|---|
| Basis | residence, worldwide income | citizenship, worldwide income |
| Tax-free | 4 587 € deduction on salaries and pensions | standard deduction $16,100 single, $32,200 joint |
| Brackets | 12,5 % to 8 342 € … 48 % above 86 634 € (nine bands) | 10 % to $12,400 … 37 % above $640,600 (seven bands; joint thresholds doubled) |
| Surcharges | solidarity 2,5 % above 80 000 €, 5 % above 250 000 € | net investment income tax 3,8 %; state income tax if you keep a state domicile |
| Dividends and interest | 28 % flat | qualified dividends 0 / 15 / 20 %; ordinary rates on interest |
| Capital gains | 28 % on securities; half of a property gain at progressive rates | 0 / 15 / 20 % long-term; ordinary rates short-term |
| Joint filing | yes, income split | yes, married filing jointly |
| Year and deadline | calendar year; 1 April – 30 June | calendar year; 15 April (15 June abroad, 15 October on extension) |
Portugal’s rates overtake the American ones early: 34,9 % applies from 29 397 € of taxable income, where a single American would still be at 22 %. For a working family the Portuguese tax is usually the higher of the two, which means the US return ends with no US tax after credits — and the Portuguese return is the one to optimise.
What the treaty says for individuals
- Residence (art. 4). If both countries treat you as resident (a green-card holder is a US resident; a citizen is not, by residence), the tie-breaker runs permanent home → centre of vital interests → habitual abode → nationality.
- Employment (art. 15). Taxed where the work is done, with the 183-day exception for short assignments paid from abroad.
- Dividends (art. 10) 15 % at source (5 % for a company holding 25 % for two years); interest (art. 11) 10 %; royalties (art. 13) 10 %. A Portuguese resident receiving US dividends therefore pays 15 % to the US and 28 % in Portugal with a 15 % credit; the citizen files both anyway.
- Capital gains (art. 14). Real estate is taxed where it is (US real property interests and Portuguese property-rich companies included); everything else only in the residence state — Portugal — subject to the saving clause for citizens.
- Pensions (art. 20). Private pensions for past employment are taxable only in the residence state; US Social Security benefits and other public pensions may be taxed by the United States, and Portugal credits the US tax. Government-service pensions (art. 21) stay with the paying state unless the pensioner is a national and resident of the other state.
- Relief (art. 25). Credit in both directions; Portugal credits US tax on income the US may tax “other than solely by reason of citizenship”; the US re-sources citizenship-only income to Portugal.
The American paperwork that does not go away
| Form | Who | Threshold | Due |
|---|---|---|---|
| 1040 with Schedule B | every citizen and green-card holder above the filing threshold | any income | 15 June abroad (15 October on Form 4868) |
| 2555 foreign earned income exclusion | employees and freelancers meeting the bona fide residence or 330-day test | up to $132,900 of earned income in 2026 | with the 1040 |
| 1116 foreign tax credit | anyone paying Portuguese tax | per income basket | with the 1040 |
| FBAR (FinCEN 114) | anyone whose foreign accounts together exceeded $10,000 at any moment | Portuguese bank, brokerage, some PPRs and insurance policies | 15 April, automatic to 15 October |
| 8938 (FATCA) | residents abroad with specified foreign assets above $200,000 at year end or $300,000 at any time ($400,000 / $600,000 joint) | accounts, foreign funds, foreign pensions, shares in Portuguese companies | with the 1040 |
| 8621 | holders of non-US funds (PFICs) | every Portuguese or European ETF, UCITS fund or unit trust | with the 1040, per fund |
| 5471 / 8858 | owners of a Portuguese company or sole-trader activity | 10 % or more of a Portuguese company | with the 1040 |
Detail on the first two lines of that table is on the FBAR and FATCA page. The Form 8621 line is the one that quietly costs the most: European funds bought through a Portuguese bank are passive foreign investment companies for the IRS, with punitive US taxation on gains and a form per fund. Americans in Portugal generally keep their investments in US-domiciled ETFs through a US broker that accepts a foreign address.
Portuguese social security and the totalization agreement
The 1989 agreement assigns each worker to one system. An employee sent to Portugal by a US employer for up to five years stays under US Social Security with a certificate of coverage; an employee of a Portuguese company pays Portuguese contributions (11 % + 23,75 %); a self-employed person pays where they reside — in Portugal, 21,4 % on 70 % of turnover, and no US self-employment tax. Credits from both countries are combined to qualify for benefits (six US credits and twelve Portuguese months are the minimums). The agreement page covers the mechanics and how Social Security benefits are taxed here.
Special regimes and what Americans can use
- NHR closed on 1 January 2024. Its successor IFICI — 20 % on Portuguese employment or business income in listed activities for ten years, foreign income exempt — is open to Americans who take a qualifying job (research, higher education, start-ups, some industrial and export companies) and were not resident in the previous five years. The IRS still taxes the income at US rates, so the saving is the difference between 20 % and the US effective rate. See NHR and IFICI for US expats.
- Roth IRAs are not recognised by Portugal: distributions are pension income here, taxed at the progressive rates, with the capital component excluded only where it can be documented.
- Portuguese property: IMT and stamp duty at purchase (7,5 % flat IMT while non-resident since May 2026), IMI yearly, AIMI above 600 000 € of tax value — see IMI and AIMI for Americans. US estate tax reaches the Portuguese home only above the $15 million exclusion; Portugal charges 10 % stamp duty on inheritances except between spouses, children and parents.
The order of the two returns
Portugal first
The Portuguese return (April–June) fixes the Portuguese tax for the year. It includes US-source income in annex J with the treaty withholding credited.
Then the United States
The 1040 on extension (15 June or 15 October) uses the Portuguese tax actually paid on Form 1116, and the FEIE on Form 2555 for salaries where that is better. Portuguese tax paid is usually enough to zero the US liability except on US-source income and on the net investment income tax, which no credit offsets.
Information returns
FBAR and 8938 from the year-end balances of every Portuguese account; 8621 for any European fund; 5471 for a Portuguese company.
State return
Only if your former state still considers you domiciled (California, New York, Virginia and a few others need a clean break); most expats file a final part-year return.
Access Portugal's accountants prepare the Portuguese return and coordinate with your US preparer — or with the enrolled agent we work with — so that the credits match on both sides and the FBAR balances come from the same statements. Ask for a two-country quote.
Questions Americans ask
Do I pay tax twice?
Rarely. Portuguese tax is credited on the US return dollar for dollar up to the US tax on the same income, and the FEIE removes up to $132,900 of salary from US tax altogether. Double tax survives only on income the credit cannot reach — the 3,8 % net investment income tax, or US-source income the treaty leaves to the US.
Is my Social Security taxed in Portugal?
Yes, as pension income at the progressive rates after the 4 587 € deduction, and the US may tax it too under article 20(1)(b) — Portugal then credits the US tax. Whether the US actually taxes it depends on your total income (up to 85 % of benefits are taxable in the US).
Can I keep my US brokerage account?
Yes, and you should: US-domiciled ETFs avoid the PFIC problem. Some brokers restrict accounts with a foreign address; check before moving. Dividends and gains are declared in Portugal at 28 % with credit for the 15 % treaty withholding.
What happens if I have never filed the FBAR?
The IRS offers the Streamlined Foreign Offshore Procedures for non-wilful failures: three years of returns, six years of FBARs, no penalty for residents abroad. It is the route most late filers take, and it must be started before the IRS writes first.
Sources and official references
- IRS — Convention between the United States and Portugal (signed 6.9.1994, effective 1.1.1996): art. 4, 10, 11, 13, 14, 20, 25; protocol saving clause — checked 18.9.2026
- Autoridade Tributária — treaty table 2026: USA row (dividends 15 %, 5 % for 25 % corporate holdings; interest 10 %; royalties 10 %) — checked 18.9.2026
- IRS — tax inflation adjustments for tax year 2026 (brackets 10–37 %, standard deduction $16,100 / $32,200, FEIE $132,900, estate exclusion $15 million) — checked 18.9.2026
- IRS — U.S. citizens and resident aliens abroad: automatic 2-month extension, further extension to 15 October — checked 18.9.2026
- IRS — Report of Foreign Bank and Financial Accounts (FBAR): $10,000 aggregate, due 15 April, automatic extension to 15 October — checked 18.9.2026
- IRS — Summary of FATCA reporting (Form 8938 thresholds abroad: $200,000 / $300,000 single, $400,000 / $600,000 joint) — checked 18.9.2026
- SSA — U.S.–Portuguese Social Security Agreement, in force 1 August 1989 (text: detached workers up to five years) — checked 18.9.2026
- Código do IRS, artigo 68.º — Portuguese brackets 2026; artigo 16.º — residence — checked 18.9.2026
- Código do IRS, artigo 81.º — foreign tax credit in Portugal — checked 18.9.2026