US Portugal Totalization Agreement: Social Security for Americans

Yes. The United States and Portugal have a Social Security agreement, often called a totalization agreement, which SSA says entered into force on 1 August 1989. It has two purposes: no double Social Security tax on the same earnings, and credits from both countries that can be combined to qualify for a benefit.

This guide covers what the agreement does for a U.S. citizen or resident who works, is sent to work, or is self-employed in Portugal. It sits beside our guide to US taxes for Americans abroad, which is the place to start for the income tax side, and our explanation of what the US-Portugal tax treaty does. It reports what the official pages say and is not legal or tax advice. For Portugal, the SSA pamphlet says the agreement covers the general social security system and special systems for certain categories of workers, including self-employed persons, and does not cover the system for civil servants.

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

We read the Social Security Administration (SSA) pages named at the end, and the IRS page on totalization agreements, on 19 October 2026. The SSA pages show no “last updated” line. The IRS page shows “Page Last Reviewed or Updated: 14-Mar-2026”, which is the most recent date on any page we read and the date of the latest information in this guide. The SSA Portugal page uses a 2022 example for work credits, so it has not been rewritten recently; the amounts it quotes are not current and we do not repeat them. We did not read the text of the agreement itself, and we did not read the Portuguese Segurança Social pages on the agreement, so what follows on Portuguese rules is what SSA says about them.

What does the US-Portugal totalization agreement do?

SSA says totalization agreements have two main purposes. First, “the Agreements prevent dual social security taxation on earnings”, which happens when a worker from one country works in another and must pay both systems. Second, they “help fill gaps in benefit coverage for workers who divide their careers” between the two countries.

For the United States, SSA says the agreements cover Social Security taxes, Medicare taxes, and retirement, disability and survivors benefits. They do not cover benefits under Medicare or Supplemental Security Income. On the Portuguese side, the SSA pamphlet says the agreement covers the general system of old-age, survivors and disability insurance and special systems for certain categories of workers, such as self-employed persons. The pamphlet also says workers exempted from Portuguese coverage pay nothing into other Portuguese programs, such as sickness, maternity, occupational injury, unemployment and family allowances, and generally cannot receive benefits from them. SSA suggests you and your employer may wish to arrange alternative protection.

The IRS makes the practical point: these agreements “must be considered when determining whether an individual is subject to U.S. Social Security/Medicare tax, or whether a U.S. citizen or resident is subject to the social security taxes of a foreign country.”

Which country’s Social Security do I pay into?

The first three rows come from the SSA page on the agreements and the fourth and fifth from the Portugal pamphlet. SSA’s agreement overview gives the general rule that an employee sent by an employer from one agreement country to another for five years or fewer stays covered by the home country. We found nothing on the pages we read that sets a different term for Portugal.

If you are an employee of a Portuguese employer, your contributions follow the Portuguese rules we describe in our guide to employee contracts and Social Security rights. To register with the Portuguese system in the first place, see our guide to the NISS social security number.

What if I work for a U.S. company from Portugal?

The pages we read do not describe remote work for a foreign employer as such, so we do not say which rule applies to a remote worker with a U.S. employer. They describe a worker sent by an employer on a temporary assignment, and they point to a point that matters in practice: for a worker transferred to an affiliate of a U.S. company, the employer must say whether the U.S. company has an agreement with the IRS under section 3121(l) of the Internal Revenue Code to pay U.S. Social Security taxes for U.S. citizens and residents employed by the affiliate. Our guide to remote work for a foreign employer covers the Portuguese side of that question. If your situation is not a clear temporary assignment, ask the employer to put the question to SSA and to Segurança Social before the work starts.

How do I prove I am exempt? The certificate of coverage

SSA says a worker exempt from one country’s taxes must document it with a certificate of coverage from the country that will continue to cover them, and that the certificate shows the effective date of the exemption. That date is generally the day you began working in the other country, “but no earlier than the effective date of the Agreement”. SSA advises asking early, preferably before the work begins.

For a Portuguese certificate for an employee in the United States, the SSA pamphlet says the employer in Portugal requests form P/USA 1 from the regional center of the Portuguese social security system where the worker is registered, and lists what the request must contain, among it the worker’s U.S. Social Security number, the date of hire, the dates of transfer and expected return, and the employer’s name and address in both countries. SSA says U.S. employers should keep certificates in case of an IRS audit and not send them to the IRS unless it asks.

For a self-employed person residing in Portugal, the pamphlet says to write to the regional center where you are registered and pay your contributions, giving your full name, date and place of birth, citizenship, country of permanent residence, your U.S. and Portuguese social security numbers, the nature of the activity, its dates and the name and address of your business in both countries. It then says to “attach a photocopy of the certificate to your U.S. income tax return each year as proof of the exemption.” Our guide to the freelancing regime in Portugal covers the registration side.

We did not use SSA’s online certificate of coverage service and do not describe its forms.

How does combining credits work for a benefit?

The Portugal pamphlet says that if you have credits in both countries you may be eligible for benefits from one or both: if you meet all the basic requirements under one country’s system you get a regular benefit from that country, and if you do not, the agreement may help you qualify, with a partial benefit from the United States based on both countries’ credits, or a Portuguese benefit that counts your U.S. credits.

For Portugal specifically, the pamphlet gives these conditions:

• Benefit from the United States: you must have earned at least six credits, generally one and one-half years of work, under the U.S. system for Portuguese credits to count. If you already have enough U.S. credits for a benefit, the United States cannot count Portuguese ones.
• Benefit from Portugal: you must have at least 12 months of coverage credited under the Portuguese system for U.S. credits to count.
• What Portugal requires on its own: the pamphlet says the old-age benefit is payable at age 66 and 4 months with fifteen years of coverage needed, and the disability benefit requires at least five years of credits. These are the figures printed on the SSA page; they may have changed, so check them with Segurança Social.
• Who pays: each country pays its own benefit.

The Portugal pamphlet says that if you live in Portugal you can contact the Federal Benefits Unit at the U.S. Embassy in Lisbon or any Portuguese social security office. Receiving the U.S. benefit while living in Portugal is a separate subject, covered in receiving US Social Security benefits in Portugal.

Does the agreement help with Medicare?

No. SSA says the agreement allows it to count foreign credits toward U.S. retirement, disability or survivor benefits, but it “doesn’t cover Medicare benefits”, and SSA cannot count credits in an agreement country to establish entitlement to free Medicare hospital insurance. For Medicare outside the United States, see our guide to Medicare and US insurance abroad.

What about Britons?

The SSA pamphlet we read is about the United States and Portugal and applies to people covered by those two systems. SSA also lists a separate agreement with the United Kingdom, but we did not read it, and we did not read any agreement between the United Kingdom and Portugal. For a Briton’s state pension and National Insurance, see our guide to the UK State Pension in Portugal.

What we read

On 19 October 2026: SSA, Totalization Agreement with Portugal; SSA, U.S. International Social Security Agreements; SSA, International Agreements (agreement descriptions); SSA, Certificate of Coverage; IRS, Totalization agreements (reviewed 14 March 2026).