Before you start: how to identify yourself to the tax office
To do almost anything on the Agencia Tributaria website (the «sede electrónica») you have to prove it is you. The main ways are Cl@ve, a digital certificate and the electronic ID card (DNIe); for the Renta a reference number also works. Pick one and set it up in good time, not on the last day.
Choose how you will identify yourself
Cl@ve is the easiest for most people: you register once and then sign in with the Cl@ve app on your phone, with no passwords to remember.
A digital certificate is a file you install on your computer or phone. It takes a bit more effort to get, but it works for almost everything and many self-employed people use it.
The electronic ID card also works if you have a card reader (or a compatible phone) and know your ID card PIN.
For the Renta there is also the reference number: a code you request with your ID and a figure from last year’s return. It only works for the Renta services, not for forms 303 or 130.
💡 Tip: If you are self-employed, keep two methods ready (for example Cl@ve and a certificate): if one fails on the last day, you still have the other.
Register for Cl@ve (only once)
On the Agencia Tributaria website, in the Cl@ve section, look for «Registrarse en Cl@ve» (register for Cl@ve). There are several ways:
Video identification from the Cl@ve app: download the official app on your phone, take a photo of your DNI or NIE and a short video of your face. It is the fastest way.
Online with an invitation letter: you request it on the website and a letter with a code to finish the registration arrives by post.
With your digital certificate or electronic ID card if you already have one, or in person at a registration office (for example of the Agencia Tributaria), with an appointment.
Depending on how you register you get a basic or an advanced level. Basic (automatic video identification or invitation letter) works for many procedures, but not all. Advanced (with a certificate or electronic ID, in person, or with the video identification reviewed by a civil servant) works for more services.
⚠️ Watch out: Cl@ve is personal: never share your access, not even with an accountant. If someone has to do things for you, use a power of attorney (last step of this guide).
How to sign in with Cl@ve Móvil
In the procedure you want to do, choose to identify yourself with Cl@ve Móvil.
Open the Cl@ve app and scan the QR code on the screen. If you cannot scan it, you will get a notification on your phone to confirm it is you.
If you prefer a digital certificate
The personal certificate is issued free of charge by the FNMT (the Spanish Royal Mint) on its website.
There are several ways to get it: request it online and prove your identity in person at an office, by video identification, with your electronic ID card or with the FNMT app on your phone.
Follow the FNMT instructions to the letter. There are usually four steps: initial setup, request, proving your identity and downloading the certificate.
💡 Tip: Keep the backup somewhere safe: if you change computer, you import it instead of requesting it again.
⚠️ Watch out: The certificate expires. Put the date in your calendar to renew it before it does.
For the Renta: the reference number
In the Renta section of the tax website, click «Obtén tu número de referencia» (get your reference number). It asks for your NIF, the expiry date of your ID card and the amount in box 505 of last year’s Renta.
If you did not file last year, or that box was 0, it asks instead for the last digits of a bank account in your name.
Keep the number: you will use it during the campaign. If you request a new one, the old one stops working.
If an accountant files for you: the power of attorney
If an accountant or a relative files your taxes, do not give them your passwords: grant them a power of attorney (apoderamiento) in the Agencia Tributaria register.
You can grant it online (with Cl@ve, a certificate or the electronic ID card), in person at an Agencia Tributaria office, or with a notarised document.
It can be general, for the procedures allowed, or only for specific ones such as the Renta or form 303. If you grant it online, the other person has to accept it before it works.
Many accountancy firms are «colaboradores sociales» of the Agencia Tributaria and can file with your written authorisation, without a power of attorney. Ask your accountant what they need.
💡 Tip: You can check and revoke your powers of attorney at any time on the tax website.
Deadlines
- Do it early: the Cl@ve invitation letter comes by post and takes a few days.
- The reference number can be requested before the Renta starts (in the last campaign, from 11 March 2026).
Videos
Finanverso video: Certificado digital FNMT para tontos: cómo conseguirlo paso a paso
Source: Agencia Tributaria (sede.agenciatributaria.gob.es), checked on 17 October 2026.
A simplified guide for orientation only. Button and menu names on the tax website may change, and your case may have exceptions. It does not replace the official information of the Agencia Tributaria or the advice of a tax adviser: always double-check before filing.