Portugal Social Security Number (NISS) for Americans and Britons
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In this article
- What the pages say, and when
- What is the NISS and who needs it?
- Who can ask for it?
- How do I ask for it?
- Which documents do I need as an American or a Briton?
- What if AIMA asks for a NISS before I have a job?
- Can I ask for the NIF, the NISS and the SNS number together?
- How do I get the number once it is assigned?
- What happens after I have the NISS?
- Pages read for this guide
- FAQ
The NISS, the número de identificação da Segurança Social, is the number that identifies you to the Portuguese social security system. As a foreigner you ask for it online (or, for the combined request, at a counter), through the Segurança Social form, attaching an identity document and proof of the reason you need it, and gov.pt says the request is free.
This guide follows the first-month order laid out in our paperwork checklist for the first month in Portugal. It reports what gov.pt and the Instituto da Segurança Social say on the day we read them. It is not legal advice, and the office that handles your request decides what it accepts.
What the pages say, and when
Related guides: the Chave Móvel Digital for foreigners, proving your address in Portugal, apostilles, translations and certified documents.
We read the gov.pt guide on requesting the NIF and the NISS (updated 2 September 2026), the gov.pt service page for the NISS (updated 3 September 2026), the gov.pt guide on taxes and social security for migrants (updated 5 May 2026) and the Instituto da Segurança Social practical guide on the NISS request for foreign citizens (version 1.18, published 24 September 2025). We read them on 18 October 2026. The most recent change we rely on is the 3 September 2026 update of the gov.pt service page, which is the date this article carries as its update date.
The Segurança Social portal pages themselves (seg-social.pt) are script-rendered and returned no text to us, so everything below comes from gov.pt and from the practical guide PDF published by the Instituto.
What is the NISS and who needs it?
gov.pt says the NISS is the number that lets you access rights and meet duties at Segurança Social, such as support and benefits and contributions. Its migrants guide adds that if you want to work in Portugal, as an employee or independently, having a NISS is mandatory, and that the number identifies you for rights such as support in case of illness, unemployment and parental leave.
The NISS is not the NIF. The NIF is the tax number from the Finanças; our guide to the Portuguese NIF for Americans and Britons covers it. The two are requested separately, with one exception described below.
Who can ask for it?
The gov.pt service page lists who can request the NISS:
- foreign persons
- Portuguese persons with a lifelong identity card (bilhete de identidade vitalício)
- legal representatives, on behalf of the foreign person
- employers, on behalf of the foreign person they are hiring
For an employer’s request, gov.pt says the employer must first have signed an employment contract with you and report the employment on Segurança Social Direta. The Instituto’s guide adds that an employer’s request serves only to assign the number, and that the employer must then tell Segurança Social online that you started work. People with a Portuguese Cartão de Cidadão get the NISS automatically.
How do I ask for it?
The Instituto’s guide says the request is made exclusively online, on the Segurança Social portal, in the Help menu under the NISS, “Atribuição de Número de Identificação de Segurança Social”. The steps it describes:
- Open the NISS request, read the general information and confirm you agree with the declarations.
- Enter the email you want tied to the request and confirm it with the code you receive.
- Complete the security check.
- Choose the reason for the request: work for an employer, independent professional activity, asking for a Segurança Social benefit, asking for support from another entity, or other.
- Upload the document that proves the reason, and say whether a legal representative is involved.
- Fill in your identity (name, date of birth, sex, marital status, parents’ names, country of nationality and of birth, identity document type, number and expiry) and your address and mobile number.
- Review the summary and submit.
Uploaded files can be PNG, JPG or PDF, up to 3 MB each. The guide says the photo on an identity document must be fully visible and without glare, and that a two-sided document is uploaded one side at a time. You get a message with a request identifier. If the reason is independent activity, you must also enter your NIF on the identification tab. For voluntary social security, the guide says to choose “other”.
Which documents do I need as an American or a Briton?
gov.pt and the Instituto’s guide divide applicants into EU, EEA and Switzerland, and third countries. The United States and the United Kingdom are not in the EU, the EEA or Switzerland. The guide defines third countries as those that are not part of the EU or the EEA and with which there is no social security agreement relevant to international coordination, and the pages do not say which group a US or UK national falls in. The two lists below are the third-country lists; ask Segurança Social which applies to you. Identity documents must be valid on the day of the online request.
| What | What the pages list |
|---|---|
| Identification | The passport; the Instituto’s guide also accepts the residence title (temporary or permanent) |
| Analysis of the request (third-country national) | A residence title; or a residence or work visa of a type the guide lists; or proof that a residence title or a CPLP residence visa was requested |
| Reason for the NISS | An employment contract (translated into Portuguese), or the start of self-employment with receipts or invoices, or a company registry certificate, or a contract with a foreign employer for digital nomads, or a document that supports voluntary social security |
| Legal representative or employer | The representative’s valid ID and an original power of attorney, or the PA-12 form with a copy of the represented person’s ID |
The visas the Instituto’s guide lists include the residence visas for employment, independent work, remote work abroad, study, research, family reunification, the job seeker visa and the digital nomad visa. gov.pt’s version of the list is shorter: passport, work visa, and a residence authorization or another civil ID from the country of origin, plus proof of the work situation and of the residence application. The Instituto’s guide is the more detailed of the two, and the gov.pt guide is newer (September 2026 against September 2025), so the two lists differ and you should ask Segurança Social which applies to you if the two disagree for your case.
Neither page describes a separate procedure for British people who hold a Withdrawal Agreement residence document, so if you hold one, ask Segurança Social what it expects. Our guide for Britons moving after Brexit explains who is in that group.
What if AIMA asks for a NISS before I have a job?
The Instituto’s guide has a section for exceptional situations. When AIMA requires that the person already has a NISS in order to grant a residence authorization that allows work, such as for holders of a job seeker visa, a student visa or a temporary stay visa for seasonal work, and the person cannot yet show a residence title, proof of a residence request or proof of work, the guide says to attach the identity documents and a declaration or request from AIMA explaining why the NISS is needed. Our guide to the AIMA residence permit process covers the application itself.
Can I ask for the NIF, the NISS and the SNS number together?
gov.pt says foreign persons with an address in Portugal can request the NIF, the NISS and the national health service (SNS) user number in a single request. The Instituto’s guide gives the conditions: you have already requested or obtained a residence authorization, or you are an EU national, or you requested or hold international protection. It lists ten counters (Espaços Cidadão) where this combined request is available, among them Lisbon (Saldanha and Laranjeiras), Cascais, Braga, Lagos, Oeiras, Olhão, Setúbal and Loures, and says you must authenticate with the Chave Móvel Digital or the European eIDAS system, with the option to activate the Chave Móvel Digital at the counter using your passport. If you already requested a NISS on the website and then use a counter, only one NISS is assigned.
On the health number, see our guide to healthcare access for newcomers.
How do I get the number once it is assigned?
The two sources describe the last step differently. gov.pt (updated 2 September 2026) says that after the request you receive a registered letter at the address you gave, saying the NISS can be collected at a Segurança Social service desk. You collect it yourself with valid ID, or a lawyer can with a professional card and an original court power of attorney, or another person with an original power of attorney or form PA-12 and the IDs. To book the desk visit, gov.pt gives the SIGA platform, the SigaApp, or the phone numbers 210 548 888 and 300 088 888 on working days from 9:00 to 18:00.
The Instituto’s guide (September 2025) describes a look-up in the portal: you enter the request ID, the email tied to the request and your date of birth, then the guide says a biometric verification gives access to a NISS proof for download; if it cannot be completed, the proof can be collected by video appointment or at a service desk. We read the portal’s own request page in a browser on 18 October 2026: before you start, it asks you to authorize Segurança Social to collect and process your personal and biometric data (for example facial image and fingerprints) to verify your identity, and says these data are deleted after the verification. That supports the biometric step in the guide, but we did not open the look-up page, so we cannot say which description of the last step applies to your request today. Follow the message you receive after submitting, and check the status of your request on Segurança Social Direta, which gov.pt names for that purpose.
What happens after I have the NISS?
The number identifies you, but it does not by itself register you as an employee or independent worker. gov.pt says employers register employees and need your address, NISS, ID and NIF; an employee’s contribution is 11% of gross pay, withheld by the employer. An independent worker pays their own contributions between the 10th and 20th of the month after the one they relate to, unless exempt. The Instituto’s guide sends a person who already has a NISS to separate practical guides for employee registration and for independent workers. For work routes, see working in Portugal as an American or Briton.
More guides on this site: registering with the SNS; U.S. Social Security and Portugal.
Pages read for this guide
All read on 18 October 2026: the gov.pt guide on requesting the NIF and the NISS for foreigners, the gov.pt service page for the NISS, the gov.pt guide on taxes and Social Security for migrants, and the Instituto da Segurança Social practical guide on the NISS request for foreign citizens and Portuguese citizens without a citizen card. A gov.pt page for the combined request was unavailable because of scheduled maintenance. The seg-social.pt request pages could not be read as text.
FAQ
Does it cost anything to get a NISS?
No. The gov.pt guide states that the request for the NISS is free.
Can my employer ask for the NISS for me?
Yes. gov.pt lists employers acting for a foreign worker among those who can ask, but the employer must first have signed an employment contract with you and report the employment on Segurança Social Direta. The employer's request only assigns the number.
Do I need a NISS to work in Portugal?
gov.pt says that to work in Portugal, as an employee or as an independent professional, having the NISS is mandatory. If you do not have one yet, you can request it.
Do Britons follow different rules from Americans?
Not on the pages we read. The guide splits applicants into people from the EU, the EEA or Switzerland, and people from a third country, and the guide defines third countries as those that are not part of the EU or the EEA and with which there is no social security agreement relevant to international coordination. The pages we read do not say which group a US or UK national falls in, so ask Segurança Social. The pages do not describe a separate procedure for Withdrawal Agreement holders, so ask Segurança Social if you hold that document.
Sources
Official pages this article was checked against, with the date we last read them.
- Como pedir o NIF e o NISS para pessoas estrangeiras em Portugal
- gov.pt, Request the Social Security Identification Number (NISS)
- Instituto da Seguranca Social, Guia Pratico Pedido de NISS for foreign citizens (1010, v1.18)
- gov.pt, Migrants: taxes and Social Security in Portugal
- NISS request page for foreign citizens, general information
About the author
See author pagePatricia Cunes writes the guides on Portuguese paperwork and the long road to settling for good: appointments with the administration, files that stall, residence renewals, and citizenship. Her work follows the steps in the order they have to happen, because the order often decides whether a file moves.
She studied Law at the Universitat de Barcelona and Migration Studies at the Universitat Pompeu Fabra, with a focus on residence and nationality procedures.
Her method is the site's: the competent authority's page is the source, the link is in the text, the date is on the page.
Her work is practical information, not legal advice. When a file needs an immigration lawyer, she says so and helps you get to the appointment prepared.
