You’ve moved to Portugal, you’ve sorted your NIF (the tax number), and then a form, an employer or your Social Security enrolment asks for something else: the NISS. And you don’t have one yet.
It feels like another wall of Portuguese bureaucracy. But in fact requesting the NISS as a foreigner is a free, mostly online process - if you know the steps and gather the right documents first.
What the NISS is (and how it differs from the NIF)
The NISS (Número de Identificação de Segurança Social) is your number with Social Security - the one you use to contribute, file declarations and access benefits. It’s not the same as the NIF, your number with the tax office (Finanças). You’ll need both: the NIF for tax, the NISS for Social Security.
If you already have a Portuguese Citizen Card, you don’t need to request the NISS - it was assigned automatically and is printed on the back. This article is for those who don’t have a Citizen Card yet.
How to request it online
The request is made on the Social Security portal (seg-social.pt):
- Go to “Sou Cidadão” (I’m a Citizen).
- Choose “Atribuição de Número de Identificação de Segurança Social (NISS)”.
- Select the option for foreign citizens.
- Fill in the form and upload the documents in a single file.
The documents depend on your nationality:
- EU/EEA or Swiss citizen: a civil ID document from your home country, your passport or your residence card.
- Third-country national: a valid identity document - your passport or a valid residence permit - plus one document proving your residence status (a visa, a residence permit or proof that you’ve requested the regularisation of your residence).
In either case, add proof of your working situation - a contract or documentation of your self-employed activity.
The request is completely free. Be wary of sites that charge to “get your NISS for you” - the official process costs nothing.
After you apply
Social Security verifies the request and notifies you of the assigned NISS - typically by registered letter. You then collect the number in person at a service centre, presenting that notification and a valid identity document.
There’s no fixed official deadline for the assignment - it depends on the verification. To avoid queues when collecting, you can book an appointment through the scheduling line (210 548 888 or 300 088 888, on working days from 9am to 6pm).
The case of Marco
Marco moved from Italy to Lisbon to work as a freelance developer. As an EU citizen, he identified himself with his passport. He submitted the NISS request online, with his documents uploaded, and later collected the already-assigned number at the service desk.
The lesson: you request the NISS online and it doesn’t hold up the rest. To open your activity at the tax office you only need the NIF, so you don’t need the NISS before - sort it out in parallel.
Careful: getting a NISS is not the same as being enrolled as a self-employed worker. The NISS is only your identification number. Enrolling as a trabalhador independente (and starting to contribute) is a separate step that happens when you open your activity at the tax office and Social Security frames you. Don’t assume the number alone starts your contributions - or that it doesn’t.
Where FIZ comes in
Once you have your NIF and NISS and open your activity, the recurring Social Security part - the quarterly declaration and contributions - is where most newcomers get lost. FIZ calculates and files your quarterly Social Security and VAT declarations automatically from the receipts you issue, so the bureaucracy stops at getting the numbers.
In summary
- The NISS (Social Security) is different from the NIF (tax office) - you need both. If you have a Portuguese Citizen Card, the NISS is already on its back.
- A foreign citizen requests the NISS free on seg-social.pt (Sou Cidadão - Atribuição de NISS). The documents vary: EU/EEA/Swiss citizens use a civil ID, passport or residence card; third-country nationals add one residence-status document (a visa, residence permit or proof of the request).
- There’s no fixed official deadline and you collect it in person. To open your activity at the tax office you only need the NIF, so you don’t need the NISS first - request it online in parallel. If you already have one but lost it, see the Help Center guide.
