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Applying for the Número de Seguridad Social: How to get your Spanish NUSS

If you want to work in Spain, start out as an Autónomo, or gain access to the public healthcare system, there's one document you can't avoid: the Número de Seguridad Social (NUSS). Without this identifier, no employer can officially hire you, you can't register as self-employed, and you can't apply for a health card either. In this guide, you'll learn what the NUSS actually is, how it differs from the Número de Afiliación (NAF) and the actual registration (Alta), which documents you need, and how to apply for the number online via the Import@ss portal or in person at the Tesorería General de la Seguridad Social. By the end, you'll know exactly which steps to take and in what order – and which mistakes cost you unnecessary time.

Applying for the Número de Seguridad Social: NUSS guide

Want to skip the trip to the authorities altogether?

What is the Número de Seguridad Social (NUSS)?

The NUSS is a personal, unique and lifelong identification code assigned to you by the Tesorería General de la Seguridad Social (TGSS). The legal basis includes the Real Decreto 84/1996 on social security. The number identifies you to the Spanish social security system in all matters: when registering as an employee or self-employed person, when receiving benefits such as unemployment pay or pension, and when registering for public healthcare in your Autonomous Community.

Important to understand: the NUSS is not a tax or ID number like the NIE, but is intended exclusively for social security matters. You generally only apply for it once in your lifetime – even if you later switch between jobs, employers, or your status as an employee versus Autónomo.

Note: Without an existing NUSS, no employment contract can be formalised – not even retroactively. So make sure to sort out this step before accepting a job offer.

NUSS, NAF and Alta: An overview of the terms

For newcomers, the three terms NUSS, NAF and Alta often cause confusion. However, they can be clearly distinguished:

Term Meaning
NUSS (Número de la Seguridad Social) A unique, lifelong identifier used by the Seguridad Social to identify you
NAF (Número de Afiliación) Is identical to the NUSS – as soon as you make your first contribution payments, your NUSS becomes an active Afiliación
Alta The actual registration with a specific employer or as an Autónomo, carried out on the basis of your NUSS

In other words: the NUSS is the entry ticket, and the Alta is the actual entry into the building. You apply for the number once – the registration (Alta) then takes place again for each new job or activity, but always under the same NUSS.

Who needs the NUSS – and who doesn't?

In principle, any person resident in Spain, regardless of nationality, can apply for the NUSS, provided they don't already have one. The requirements differ depending on status:

Target group Requirement
Spanish nationals An existing DNI is usually sufficient as proof of identity
EU citizens resident in Spain Valid NIE number plus passport or national ID card
Non-EU foreign nationals Valid NIE, current residence permit or visa, passport
People without prior employment Can apply for the NUSS as a private individual even before starting work

Please note: Without an existing NIE number, you generally cannot apply for the NUSS. Sort out your NIE application first before applying for the social security number. You can find more on this in our guide to Residencia in Spain.

Requirements: these are the documents you'll need

For the application – whether online or in person – you should have the following documents ready:

Document Why you need it
ID document (DNI, NIE or passport) Proof of identity to the TGSS
Application form Filled in automatically online via Import@ss, or available in paper form at the office
Residence permit or visa (for non-EU citizens) Proof of legal residence status
Digital identification (Certificado digital, Cl@ve or SMS verification) Required for the online application via Import@ss

If you don't yet have a Cl@ve account or digital certificate, it's worth taking a look at our guide to Applying for the Certificado Digital & Cl@ve – this step not only makes applying for the NUSS easier, but also simplifies dealings with authorities in general later on.

Step by step: applying for your NUSS online via Import@ss

The standard route in 2026 is via the Import@ss online portal of the Tesorería General de la Seguridad Social. The process is completed in just a few minutes:

A three-phase route to the Número de Seguridad Social: first the NIE must be in place, then you apply for the NUSS free of charge in about five minutes online via Import@ss, and finally comes the actual registration (Alta) with an employer or as a self-employed worker. You are given the number once in your life; without a NIE the application is rejected.
  1. Go to the Import@ss portal of the TGSS (portal.seg-social.gob.es).
  2. Select the option "Solicitar el número de la Seguridad Social".
  3. Identify yourself using a Certificado digital, Cl@ve or SMS verification.
  4. Fill in the requested personal details and upload the required documents (ID, and residence permit if applicable).
  5. After review, you will receive your NUSS by email or as a direct download.

Note: The online application is free of charge. Never pay third-party providers or agencies for this step – processing by the TGSS itself is free.

Alternative: applying for the NUSS in person at the TGSS

Anyone without a Cl@ve account, digital certificate or Spanish mobile number for SMS verification can still apply for the NUSS in person at an office of the Tesorería General de la Seguridad Social. This usually requires a prior appointment (cita previa).

Criterion Online (Import@ss) In person (TGSS office)
Time required approx. 5 minutes Appointment (cita previa) required, waiting time varies by region
Identification Certificado digital, Cl@ve or SMS In-person attendance with original documents
Cost 0 euros 0 euros
Suitable for anyone with a NIE plus digital identification anyone who does not (yet) have digital access

Always bring your original ID document if you choose the in-person route – copies are generally not accepted.

What happens after the NUSS is allocated?

The allocation of the NUSS (Asignación de NUSS) initially only registers you in the Seguridad Social system. It is only with the actual registration – the Alta – that the number is actively used, for example because an employer registers you or you register yourself as an Autónomo. Until then, the NUSS remains "dormant", but is valid and available.

As soon as you start working or become self-employed for the first time, this number is also used to maintain your Vida Laboral (employment record), which later documents claims to unemployment benefit or pension.

NUSS and health insurance: the next step

With the NUSS alone, you are not yet automatically covered by health insurance. Only through registration (Alta) with an employer or as an Autónomo do you gain entitlement to public healthcare, which is then accessed via the Tarjeta Sanitaria of your Autonomous Community. Anyone not yet working in the meantime should look into private cover in parallel – more on this in our guide to Health insurance in Spain and to the Healthcare system.

What comes next? Alta with a job or as an Autónomo

Once you have your NUSS, the actual registration process follows:

Situation Next step
Employment Your employer registers you for Alta under your NUSS – usually on your first day of work
Self-employment (Autónomo) You register yourself as an Autónomo, usually at the same time as registering with the tax office
Several activities in parallel A combination of employment and self-employment is possible under the same NUSS (Pluriactividad)

If you're starting out as self-employed, it's worth taking a look at our guides on Tarifa Plana for Autónomos, on Bookkeeping as an Autónomo and on distinguishing a possible Falso Autónomo. Anyone working both as an employee and self-employed can find further details under Pluriactividad in Spain.

Most common mistakes when applying for the NUSS

  • Missing NIE: Without a valid NIE number, the application will be rejected, both online and in person.
  • Duplicate application: Anyone who already has a NUSS (for example from a previous stay in Spain) should retrieve it instead of applying for a second one – duplicate numbers cause problems with later registrations.
  • Payment to third-party providers: The application itself is free of charge. Payments to alleged intermediaries for the mere allocation are unnecessary.
  • Confusion with the Alta: Some expats believe that with the NUSS they are automatically health-insured or registered – in fact, this requires an additional registration step (Alta).
  • Missing digital identification: Anyone who tries to start online without Cl@ve, a digital certificate, or a Spanish SMS number will fail at the identification step and will have to switch to the in-person route.

Checklist: applying for the NUSS in Spain

  • NIE number in hand
  • Passport or ID card ready
  • For non-EU citizens: valid residence permit or visa available
  • Cl@ve account, digital certificate, or Spanish mobile number set up for SMS verification
  • Import@ss portal accessed and the option "Solicitar el número de la Seguridad Social" selected
  • If no digital access is available: appointment (cita previa) booked at a TGSS office
  • After receiving the NUSS: registration (Alta) with an employer or as an Autónomo prepared

Conclusion

The Número de Seguridad Social is one of the most unspectacular yet most important steps on your path to living and working in Spain. It costs nothing, can be applied for online in just a few minutes since digitalisation via Import@ss, and stays with you for life from the moment it is issued – no matter how often you later change employer, industry, or your status between employee and Autónomo. The only important thing is the right order: first NIE, then NUSS, then the actual registration (Alta) for employment or self-employment. Anyone who knows these three steps saves themselves unnecessary trips to the authorities and duplicate applications.

Official sources

How much does it cost to apply for the NUSS?
Applying for the Número de Seguridad Social is free of charge, whether online via Import@ss or in person at the TGSS. Payments to third-party providers for this purely administrative step are not necessary.
Do I need the NIE to apply for the NUSS?
Yes, without a valid NIE number you generally cannot apply for the NUSS, as it is required as proof of identity for foreigners.
Is the NUSS the same as the NAF?
Yes, the NUSS and the Número de Afiliación (NAF) are identical. As soon as you make your first contribution payments, your assigned NUSS becomes an active Afiliación.
How long does the online application via Import@ss take?
The online process via the Import@ss portal can usually be completed in around five minutes, provided you have the necessary documents and a digital identification method ready.
Can I apply for the NUSS without a Certificado digital?
Yes, as an alternative to the Certificado digital, you can identify yourself via Cl@ve or SMS verification. Anyone without either of these options can apply for the NUSS in person at a TGSS office.
Do I need to reapply for the NUSS for every new job?
No, the NUSS is assigned only once in a lifetime and remains permanently valid, regardless of how often you change employers or switch between employment and self-employment.
What is the difference between the assignment of the NUSS and the Alta?
The assignment (Asignación de NUSS) is the one-time registration of your person in the Seguridad Social system. The Alta is the actual, active registration with a specific employer or as an Autónomo based on this number.
Where can I find my NUSS if I already have one?
Via the Import@ss portal of the Tesorería General de la Seguridad Social, you can retrieve your existing NUSS instead of accidentally applying for a second one.