Cl@ve: activate Cl@ve Firma and add an extra mobile (Gestión 7)

What you need to have to hand

1. DNI o NIE en vigor and its número de soporte (the one on the back).
2. Your main mobile and the extra mobile you want to add (both must receive SMS).
3. Active email address.
4. App Cl@ve installed and notifications enabled.
5. If you have a NIE: TIE or passport for in-person ID check.

Documentation

• DNI o NIE en vigor.
• Número de soporte of the document.
• TIE or passport if you are a foreigner with NIE.
• Proof of cita previa if you will register in nivel avanzado.
• Phones to link and access to their SMS messages.

Step by step

1. Check your level: go to https://clave.gob.es and sign into the Área personal (Mi Cl@ve) with Cl@ve PIN/Permanente. If it shows "nivel avanzado", you're set.
2. Book an appointment if you're not advanced: AEAT at https://sede.agenciatributaria.gob.es/Sede/cita-previa.html or Seguridad Social at https://sede.seg-social.gob.es/wps/portal/sede/sede/Cita+Previa. Reason: registro Cl@ve.
3. ID check: attend the appointment with your DNI/NIE (and TIE/passport if needed). They will register you in Cl@ve nivel avanzado on the spot.
4. Activate Cl@ve Firma: return to https://clave.gob.es > Mi Cl@ve, go to Cl@ve Firma, accept terms and confirm via the App Cl@ve or SMS.
5. Add the extra mobile: in Mi Cl@ve open the phone/device management, add the new number and verify it with the SMS. Keep both numbers active just in case.
6. Test it: log into https://sede.agenciatributaria.gob.es with Cl@ve. If you can sign a query or a draft without submitting anything, it's ready.

Tricks that save time

• Two routes for appointments: if AEAT has no slots, try TGSS. Often one line moves faster than the other.
• Add the second phone before you change the main one. Obvious, but many people get locked out on the day they switch SIMs.
• Keep App Cl@ve notifications on. Without them, Cl@ve Firma won't prompt you and you'll hit errors.
• Use reliable SMS numbers: avoid corporate numbers with weird filters or lines routed through PBXs. Use a normal personal line.
• Test on a real process: AEAT's web works well with Cl@ve. If it works there, it will work in most places.

Common mistakes to avoid

1. Going to activate without nivel avanzado and expecting Cl@ve Firma to appear. It won't.
2. Adding an extra mobile that can't receive SMS. No SMS = no linking.
3. Changing phone without unlinking the old one. Result: lockout and a trip back to the office.
4. App Cl@ve muted or restricted by battery saver or notification settings. The approval never arrives and you panic.
5. Leaving appointments to the last minute: if you have a deadline, you gamble. Book early or try a different administration with free slots.