Do US citizens in Portugal have to file taxes in both countries?

Two filings, one tax bill, is the normal outcome for Americans in Portugal. The work is in the paperwork, not in the money.

The Portuguese side

Once you cross 183 days or keep a home in Portugal with the intention of living in it, you are resident and taxed on worldwide income. Modelo 3 is filed from 1 April to 30 June of the year after the income year, with any balance due by 31 August. Rates run from 12.5 to 48 percent in 2026.

The US side

Citizenship based taxation means the 1040 never stops, whatever your Portuguese status. Two tools stop the same income being taxed twice.

The foreign tax credit gives you a dollar for dollar credit for Portuguese tax paid. Since Portuguese rates reach 48 percent against a US top rate of 37 percent, the credit normally covers the US liability in full and leaves excess credits to carry forward.

The foreign earned income exclusion removes up to 132,900 USD of earned income for tax year 2026, up from 130,000 USD for 2025, but you have to qualify, usually through the physical presence test of at least 330 full days in a foreign country over 12 consecutive months. It also has a cost: excluded income is not earned income for Roth IRA contribution purposes. For most people in Portugal the credit beats the exclusion, and the exclusion earns its place mainly for lower earners and for people taxed at the IFICI flat 20 percent. Our full comparison of the credit and the exclusion runs both mechanisms with worked numbers.

The reporting layer

An FBAR is due whenever your foreign accounts together top 10,000 USD at any point in the year, and FATCA Form 8938 may apply on top. Non US funds and many European ETFs are PFICs, with punitive US treatment, which is why American residents in Portugal usually keep investing through US brokers.

Pensions and Social Security

US Social Security is taxed by the US under Article 20(1)(b) of the treaty. Whether Portugal may also tax it as foreign pension income is disputed among advisers; our answer on US Social Security in Portugal sets out both readings. 401(k) and traditional IRA withdrawals are taxable in Portugal at progressive rates.

The Portugal income tax and residency guide sets out the Portuguese half in full.