The Spanish social security number: what the TGSS actually issues

The TGSS page defines the act: affiliation is an administrative act by which the Tesorería General de la Seguridad Social recognises the inclusion in the system of a person carrying out, for the first time, an activity that brings them within its scope — it is obligatory for those included, and done once for life. Alongside it, the TGSS assigns a Número de Seguridad Social to each citizen to identify them in their relations with the system — the number employers ask for before the first contract is signed.

Source: Seguridad Social (TGSS) — Afiliación y Número de la Seguridad Social, read 10 September 2026.

Two official routes on the same page: the paper-form route — modelo TA.1, «Solicitud de Afiliación/Número de Seguridad Social» — and the online route: with a digital certificate you can process the request directly through the Asignación de número de Seguridad Social service of the Sede Electrónica. For a new arrival the practical sequencing is NIE first (Spanish systems key on it), then the NUSS before day one of work — and import@ss, the TGSS's portal, is where the number lives afterwards.

Source: TGSS — formas de practicar la afiliación, read 10 September 2026.

Keep the identifiers apart: the NIE is your general foreigner ID number (police-issued, on everything); the TIE is the residence card; the NUSS is the social-security system's own identifier — the one your employer, your contributions record and eventually your Spanish pension hang off. Health-system access for workers follows affiliation; for non-working residents the routes in our Spanish healthcare registration guide apply.

Source: TGSS — Afiliación de trabajadores, read 10 September 2026.