To install the ACA Plus certificate, first check which one you have. With the card, install the Bit4id manager program published by the Spanish Bar and connect the reader. With the certificate as software, download the .p12 file from the ACA Zona de usuario (user area) and import it: double-click on Windows, Keychain Access on a Mac.
What is the ACA certificate and what changes with ACA Plus?
The ACA certificate is the electronic signature of the Spanish legal profession (Abogacía Española), which members of the Bar have been using online since 2003. It is issued by the Autoridad de Certificación de la Abogacía (ACA, the Spanish Bar's certification authority), part of the Consejo General de la Abogacía Española (the General Council of Spanish Lawyers), and it is used for procedures with public administrations (LexNET, the electronic filing system of the Spanish courts; the Agencia Tributaria, the Spanish tax agency; Social Security), to access the RedAbogacía services and to sign documents, invoices and emails.
The renewed version, ACA Plus, started being issued in November 2024, and the migration ended in July 2025 with 104,312 lawyers using it, more than half with both formats. “The project has meant renewing the electronic certificates, enabling them both as a cryptographic card and as software,” explained Miguel Hermosa, chair of the Council's Digital Justice subcommittee.
| ACA Plus on a card | ACA Plus as software | |
|---|---|---|
| Signature, according to the Council | Qualified, “equivalent to a handwritten signature” | Advanced |
| Where it is | On the card's chip, protected by a PIN | In a .p12 file that you install on the computer |
| Systems | Windows and Mac (there is also a program for Linux) | Windows, Mac, Android and iOS |
| What you need | A reader and the Bit4id manager program | The password you set when you downloaded it |
| How it appears when choosing a certificate | FIRST NAME SURNAMES | FIRST NAME SURNAMES (SW) |
The Council presents the software one as “the certificate you can use for procedures that do not require a qualified signature”. If a procedure requires a qualified signature, it has to be the card. And a practical tip from the Ilustre Colegio de la Abogacía de Madrid (ICAM, the Madrid Bar Association): on the computers in the lawyers' rooms at the courts, use the card and not the software certificate.
How do you apply for the ACA Plus certificate?
The ACA Plus certificate is requested in person at your Colegio de la Abogacía (your local Bar Association): according to the Council, it “can only be done in person”. There you prove your identity and sign the contract. It is the required step if it is your first certificate, if the one you had has expired or been revoked, or if you are still on the old ACA, because the campaign to switch to ACA Plus online has ended.
- Card: the Bar Association gives you the card with the certificate already issued and its PIN.
- Software: you receive an email when it has been issued and you download it yourself from the ACA Zona de usuario (in Spanish).
If you already have a valid card, the software certificate is obtained from the website without going back to the Bar Association: that is the prerequisite set by the Council. Its ACA Plus application page (in Spanish) does not say what documents each Bar Association asks for or whether you need an appointment, so ask at yours.
How do you install the ACA certificate on Windows?
On Windows, the card needs the Bit4id manager program and the software certificate is imported with a double-click. The programs and guides are on the Council's installation guides and software page (in Spanish), whose compatibility table (updated on 6 February 2026) supports Windows 10 and 11 with Chrome, Edge, Opera and Firefox.
With the card and the reader
- Download and install Bit4id manager for Windows (version 10.835 as of 23 October 2026) from that page. The Bit4id manual asks for administrator permissions and a restart when you finish.
- Connect the reader to a USB port and insert the card. The ACA reader doesn't need drivers: only if the computer doesn't detect it, install the reader's drivers (MiniLectorACA for Windows), on the same page.
- Open Bit4id PKI Manager, choose the card, click Iniciar sesión (log in) and enter the PIN. Your certificates should appear in the Certificados (certificates) tab, with their expiry date.
- Edge, Chrome and Opera need nothing else: according to the Bit4id manual, the card's certificates are added automatically to the Windows certificate store. Firefox has its own store: check it in Settings, Privacy & Security, View Certificates.
With the software certificate
First you download the file from the Zona de usuario (the Council recommends Edge or Chrome for this step):
- Go to the Zona de usuario and choose «ACA Software o ACA Tarjeta» (ACA software or ACA card) if you already have the card in the reader, or «Usuario y código de un solo uso» (user and one-time code) if not. With the second option you enter your DNI (Spanish national ID number) and your email and receive a code by email or by SMS (the guides differ).
- Open the certificates bar and click Exportar Certificado (export certificate). Its name changes between guides: «Emitir Certificados» on the Council's page and «Certificados en Software» in its Windows guide.
- Click Descargar documento (download document) to see the contract, then Aceptar (accept), and tick «He leído y acepto los términos y condiciones del uso del certificado en software» (I have read and accept the terms and conditions of use of the software certificate).
- Enter a password twice and click Exportar (export). A PKCS#12 file (.p12 or .pfx) is downloaded to the Downloads folder. Keep it in a safe folder and don't lose the password: the Council describes it as essential for installing it.
Then comes the secure installation from the Council's guide for Windows, the one that asks for a password every time you use the certificate:
- Double-click the .p12 file. The Windows Certificate Import Wizard opens.
- Choose Current User (recommended: only your Windows user will be able to use it) and click Next; leave the file that comes selected and click Next again.
- Enter the file's password. Tick Enable strong private key protection (recommended) and leave unticked the option that makes the key exportable (not recommended). Click Next, Next and Finish.
- In the window that appears, click Set Security Level, choose High, create the password it will ask for every time you use the certificate and click Finish and OK.
Installed this way it works in Edge and Chrome. For Firefox you have to import it separately, according to the ICAM guide: three-line menu, Settings, Privacy & Security, Certificates, View Certificates, Your Certificates tab, Import, and the file's password.
How do you install the ACA certificate on a Mac?
On a Mac, the card uses Bit4id manager for macOS and the software certificate is imported in Keychain Access. The Council's compatibility table supports macOS Tahoe, Sequoia and Sonoma with Chrome, Edge, Opera, Safari and Firefox.
With the card and the reader
- Download Bit4id manager for Mac (version 10.836 as of 23 October 2026) from the Council's guides page and install it with administrator permissions. Restart when you finish, as the Bit4id manual says.
- Connect the reader and insert the card. The reader's drivers (MiniLectorACA for Mac) are only needed if the Mac doesn't detect it.
- Open Bit4id PKI Manager, log in with the PIN and check that your certificates appear.
- Safari needs no configuration, according to the Bit4id manual. If Firefox doesn't see the card, the manual explains how to load its library in Settings, Privacy & Security, Security Devices, although since macOS Big Sur that library is built in.
The ICAM offers a way out for anyone who can't get the Mac to read the card: log in to the Zona de usuario with «Usuario y código de un solo uso» and download the software certificate, which doesn't need a reader.
With the software certificate
Download the .p12 file with the same Zona de usuario steps as on Windows and follow the Council's guide for Mac:
- Open Keychain Access: in the Mac menu bar, Go, Utilities, Keychain Access.
- Select login and go to the My Certificates category.
- Choose File, Import Items (on a Mac in Spanish, «Importar ítems» or «Importar elementos» depending on the version, the ICAM notes), select the .p12 or .pfx file and click Open.
- Enter the certificate's password and click OK. The Mac may also ask for your user password to modify the keychain.
- Double-click the certificate and, under Trust, set When using this certificate to Always Trust.
With that it works in Safari and Chrome. Firefox, as on Windows, needs you to import it from its own settings.
How do I check that the ACA certificate works?
The most direct test is to log in to the ACA Zona de usuario with the «ACA Software o ACA Tarjeta» button. If the browser lets you choose your certificate and you get in, it is correctly installed in that browser. To see which certificates you have and when they expire:
- Card: Bit4id PKI Manager shows, after the PIN, each certificate with its expiry date.
- Windows: type certmgr.msc in the Start menu and open Personal, Certificates (as the Bit4id manual indicates).
- Mac: Keychain Access, login, My Certificates.
When choosing a certificate in the browser, look at the name. According to the Council, the ACA Plus card certificate appears only as your first name and surnames in capitals, and the software one with (SW) after them. The old ACA can be told apart because it starts with the word NOMBRE (Spanish for “name”) in capitals, includes the DNI and has an earlier issue date.
To sign, LexNET uses Autofirma, the Spanish Government's signing application, which is available at firmaelectronica.gob.es (in Spanish). As of 23 October 2026 it offers version 1.9 for Windows and 1.9.1 for Mac (Intel or Apple M1 and later), with a separate 1.9.2 for macOS Tahoe 26.4 and 26.4.1. And before turning a brief that comes out of Word into a PDF, remove the revision marks: we explain how in track changes in Word.
Why isn't my ACA certificate working?
The official guides cover five kinds of failure: reader, PIN, expiry, browser and signing platform.
The computer doesn't recognise the card or the reader
Check that you have Bit4id manager installed, which the Council describes as “required for using the card certificate”. If the computer doesn't see the reader, install its drivers (MiniLectorACA). And check the compatibility table: another combination of system and browser may work, but it has no technical support.
Card blocked: the PIN and the PUK
The ACA card is blocked after the wrong PIN is entered three times. It is unblocked with the PUK, the other code assigned when the certificate was issued:
- Open Bit4id PKI Manager.
- Click Desbloquear el PIN (unblock the PIN), in the right-hand margin of the window according to the guide from the Colegio de la Abogacía de Murcia (ICAMUR, the Murcia Bar Association).
- Enter the PUK and the new PIN, which can be the same one you had, and click OK.
ICAMUR warns that the PIN created at the Bar Association has 6 to 8 characters, even if the program says the minimum is 4. If you switched from the old ACA, the PIN is the one you had before. Without the PUK, you have to request a new card from your Bar Association, which keeps neither the PIN nor the PUK. And don't push your luck with the attempts: the Bit4id manual warns that three wrong PUKs block the card completely.
I have forgotten the software certificate password
According to the Council's FAQ, you just log in to the Zona de usuario, select the certificate, click Descargar (download) and create a new password: you can download it as many times as you like. Its page on obtaining the certificate says, however, that if you lose the file or the password “a new certificate will have to be issued”. Try the first option and, if it doesn't let you, call support.
Expired or revoked certificate
ACA's terms of use set a validity of three years for the certificate. If it has expired, the Council sends you to the Bar Association to request a new one. To revoke it, it also refers you to your Bar Association, and for an urgent revocation of an ACA Plus it gives an email address staffed 24 hours a day: revocacion@acabogacia.org. As for LexNET, its help says that after renewing the certificate you don't need to register again.
It fails in the browser, in LexNET or when signing
- «No puede contactar con Autofirma» (cannot contact Autofirma) when signing in LexNET: the Council suggests opening Autofirma, Herramientas, Restaurar instalación (Tools, Restore installation), ticking «Configurar Firefox» (configure Firefox), starting the restore and restarting. If it persists, install version 1.8.3 of Autofirma (the downloads page offers it for Windows and Linux) and, if that doesn't work either, write to LexNET support (in Spanish).
- Adobe says the signature is not valid on a PDF signed with ACA Plus: the Council says to go to Menu, Preferences, Trust Manager, tick Load trusted certificates from an Adobe EUTL server and click Update Now.
- Card with two certificates: the LexNET help warns that all the certificates on the card must be valid and that you have to choose the same one throughout the session. If the old ACA is still there, the Council explains how to delete it with Bit4id PKI Manager (log in, open the certificate, three-dot menu, «Eliminar certificado», that is, delete certificate).
- An e-government site shows your first surname twice: it is an issue that some public administrations have with the ACA Plus card and compound first names or surnames; until it is resolved, the Council suggests using the software certificate.
If none of this works
ACA technical support answers on 91 150 10 03 and 93 014 10 01, Monday to Friday from 8:30 to 14:30 and from 15:30 to 20:00, and at soporte.tecnico@redabogacia.org. Your Bar Association may also have its own support. This guide brings together what the Council, two Bar Associations and the card manufacturer publish, and menus change between versions: if something doesn't match your screen, the most recent official guide takes precedence.
And the brief you are going to sign, dictated
The ACA certificate takes care of the signature; the brief has to be drafted first, and that can be done by speaking. We explain the method in how to dictate a legal brief by voice, and what to check before signing in the drafting mistakes flagged by the Libro de estilo de la Justicia (the Spanish justice system's style guide).
With ablalo you dictate in Spanish in any program on Windows or Mac (Word, your email, the browser or your case management software) with a keyboard shortcut. It punctuates on its own, recognises more than 30,000 Spanish legal terms out of the box and your voice is transcribed on your computer: the audio is not uploaded to any server. The signature is still up to you and your ACA.
In short
The ACA Plus certificate is requested in person at the Bar Association and comes in two formats. The card gives a qualified signature and needs a reader and Bit4id manager. The software one gives an advanced signature: it is downloaded from the Zona de usuario as a .p12 file and imported with a double-click on Windows or in Keychain Access on a Mac. If it fails, check the program and reader, PIN and PUK, expiry, browser and Autofirma; ACA support is on 91 150 10 03.
Sources (all in Spanish): Consejo General de la Abogacía Española, ACA Plus, Request your ACA Plus certificate, Switch to ACA Plus, Get your software certificate, Installation guides and software (with the installation guides for Windows and Mac and the guide to issuing the software certificate, version 4.0), ACA Plus FAQ, blocked card, deleting the old ACA from the card, notice on compound surnames, Revoke or check your signature, Technical support, Terms of use of ACA certificates and the news items of 25 October 2024 and 15 July 2025; Ilustre Colegio de la Abogacía de Madrid, ACA Plus guides for Windows and Mac; Colegio de la Abogacía de Murcia, unblocking the PIN of the cryptographic card; Bit4id, user manuals for Windows and macOS, linked from the Council's guides page; Ministry of Justice, LexNET FAQ; Government of Spain, Autofirma downloads. Checked on 23 October 2026.
Frequently asked questions
How do you install the ACA certificate on a Mac?
It depends on the format. With the card, install the Bit4id manager for Mac published by the General Council of Spanish Lawyers, restart and connect the reader. With the software certificate, open Keychain Access, go to login, My Certificates, use File, Import Items with the .p12 file and set the certificate to Always Trust.
Why doesn't my ACA digital certificate work on my computer?
The causes listed in the official guides are that the Bit4id manager program is missing or the computer doesn't detect the reader, that the PIN is blocked, that the certificate has expired or been revoked, or that the browser doesn't have it: Firefox needs the software certificate imported separately. If it fails when signing in LexNET, the Council suggests restoring the Autofirma installation.
What do I do if my ACA card is blocked?
The card is blocked after three wrong PINs. Open Bit4id PKI Manager, click Desbloquear el PIN (unblock the PIN) and enter the PUK and a new PIN. If you don't have the PUK, you have to request a new card from your Bar Association, which keeps neither the PIN nor the PUK.
Can the ACA certificate be installed on a mobile phone?
Only the software certificate: the Council publishes guides for Android and for iOS (in Spanish). Its Android guide warns that websites that ask you to sign will probably not work on the phone, because they usually require components that don't exist for mobile devices. The card is for the computer.
How long does the ACA Plus certificate last?
Three years, according to the terms of use of the Autoridad de Certificación de la Abogacía. When it expires, you have to request a new one from the Bar Association; in LexNET you don't need to register again with the renewed certificate.
Can I have the card and the software certificate at the same time?
Yes. The Council explains that the two formats are compatible and can be used at the same time, and with a valid card the software certificate is downloaded from the Zona de usuario without going back to the Bar Association. In the browser list, the software one has (SW) after the name.
What is the ACA technical support phone number?
91 150 10 03 and 93 014 10 01, Monday to Friday from 8:30 to 14:30 and from 15:30 to 20:00, and the email address soporte.tecnico@redabogacia.org. For LexNET problems, the Ministry of Justice has its own support channel (in Spanish).