What the number is
The NUSS (Número de la Seguridad Social) is the number Social Security uses to identify you; it is also called the affiliation number (NAF). You need it for your first registration (alta) when you start working and for pensions, allowances and benefits; the regional health system uses it to issue your health card. It is unique for life and never needs renewing.
You may already have one
- You already have a number if you have ever worked in Spain or were covered by the school insurance (Seguro Escolar).
- In the Importass app the number appears on the home screen after you sign in. You can download a document proving it (Acreditación del NUSS) as a PDF at any time; without electronic ID, fill in your details, take a selfie and attach a photo of your ID.
Who applies and when
Anyone who does not yet have a number can request one at any time. Employers often do it when hiring someone for the first time, but you can also apply yourself — in Importass, on the website or in the app.
How to apply in Importass
You need your DNI or NIE details, a mobile phone, an email address and your home address. With Cl@ve or a digital certificate, Social Security says the system assigns the number, shows it on screen and lets you download the supporting document straight away.
- Without Cl@ve or a certificate (adults or emancipated minors): apply in your own name, fill in your details, take a selfie holding the front of your ID and attach photos of both sides of your DNI/NIE. Emancipated minors also need proof of emancipation. You cannot sign in by SMS until you have a NUSS.
- For a child, the mother, father or legal guardian applies: their own details, selfie and photo of their DNI/NIE/passport, a completed TA.1 form with the child’s details, a photo of the child’s DNI, NIE or passport, and a copy of the libro de familia or proof of guardianship.
- Social Security recommends downloading and filling in the TA.1 form and any other documents before you start the procedure.
What comes next
- Employment: your employer registers you (alta) with Social Security. When you start working, the number becomes your affiliation number.
- Self-employed people (autónomos) and employers of household staff handle registration and changes themselves in Importass; that is also where you get your employment history report (informe de vida laboral).
- The SIP health card in the Valencian Community is a separate procedure that uses your NUSS.