NUSS in Spain: what the social security number is

What is the NUSS?

NUSS stands for Número de la Seguridad Social; on the pages of the Tesorería General de la Seguridad Social (TGSS) it is also called the Número Único de la Seguridad Social. It identifies a person in their dealings with the Seguridad Social [1][2]. It is sometimes called the NISS, but the official Spanish sources we opened use NUSS, and that is what we write.

The NUSS is the same as the Número de Afiliación (NAF): it “turns into” the NAF when a person first starts work that brings them into the system, under any scheme: general, autónomos, maritime [1][2]. Article 15 of the Ley General de la Seguridad Social describes afiliación itself as single for life and for the whole system [4]. The TGSS adds that the NUSS does not need updating [2].

How does the NUSS differ from the NIE and the tarjeta sanitaria?

For the NUSS you will need your NIE, DNI or passport details, but the NIE on its own does not give you a Seguridad Social number. On the NIE and residence permits: NIE, TIE and residence permit: what is the difference. What alta and RETA are is explained in the article on RETA and alta.

Who needs a NUSS?

The NUSS is needed for your first registration with the Seguridad Social when you start work, and for pensions, benefits and other payments [3]. The regional health system uses it to issue the tarjeta sanitaria and grant the right to healthcare [1][3]. If a Spanish company hires you, it will arrange the number [1].

There are other groups too: students under 28 in official programmes (from the third year of ESO to the end of the third university cycle) get their own number as part of the Seguro Escolar; since 1 January 2024 students on work placements, paid or unpaid, are included in the system, and they also need a NUSS [1].

TGSS sources do not say whether a DNV holder who works for a foreign employer and is not registered with the Seguridad Social in Spain needs the number. It depends on the case and on how you work: there is a separate piece on social security on the DNV.

How do you get a NUSS?

1. If a company hires you and you have no number, the company applies for it; otherwise request the number yourself through the Importass service “Solicitar el Número de la Seguridad Social” [1][3].
2. Have ready your NIE or DNI details, mobile phone, email and home address [3].
3. Identify yourself with Cl@ve, a digital certificate or DNIe [1]. If you have none of these, attach photos of both sides of your document and a selfie, and fill in form TA.1 [3].
4. After the request the system assigns a number, and you keep the confirmation document, which can be downloaded and printed [1][2].

The step-by-step procedure is described in the article how to get a social security number. For a child, the request is made by a parent or guardian with the child’s documents and proof of parental authority [3]. The service page does not mention any fee for the NUSS; no cost is mentioned on any of the TGSS pages we read.

Where to find a NUSS that has already been assigned?

You may already have a number if you have worked in Spain before or were covered by the Seguro Escolar [3]. You can find it in your Importass personal area after identifying yourself, where you can also download the confirmation document; the number also appears on your nómina, your employment contract and the informe de vida laboral [1]. Do not use third-party websites to request the number: the service is on the official TGSS portal.

What we do not know: whether particular TGSS offices ask for extra documents when you apply in person, and how quickly Barcelona processes a request without electronic identification. We have not found official information on this. If you are choosing a residence permit route that allows you to work, see the work route card and the overview on the page residence permit in Barcelona.

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ReloVictory · Sources reviewed 02.10.2026 · Not a substitute for individual legal advice.