Autofirma
Autofirma is a free desktop application developed by the Spanish government (Ministerio de Asuntos Económicos y Transformación Digital) that allows you to digitally sign documents using your Certificado Digital. It is the standard signing tool used across virtually all Spanish government electronic portals: the Agencia Tributaria (for filing Modelo 036, Modelo 100, Modelo 303, and other tax forms), the UGE-CE (for submitting Digital Nomad Visa applications via the MI-T form), the Seguridad Social portals (for autónomo registration and contribution management), and the sede electrónica of most other Spanish government bodies.
When you encounter Autofirma
You need Autofirma any time a Spanish government website asks you to sign a document or form electronically. The most common scenarios for foreign residents are filing tax returns at the Agencia Tributaria, submitting the MI-T form for a Digital Nomad Visa application via the UGE-CE portal, signing TGSS forms for autónomo registration or changes, and submitting appeals (recursos) electronically. Without Autofirma installed on your computer, you cannot complete these processes online. The alternative is visiting the relevant office in person, which defeats the purpose of having a Certificado Digital.
How to install Autofirma
Autofirma is available for Windows, macOS, and Linux. You download it from the official government website at firmaelectronica.gob.es/Home/Descargas.html (not from any third party site). The installation is straightforward: download the installer, run it, and follow the prompts. On macOS, you may need to allow the application in your security settings because it is not distributed through the App Store. On Windows, the installer may require administrator privileges.
After installation, Autofirma integrates with your browser. When a government portal asks you to sign a document, it launches Autofirma automatically (or via a browser plugin). You select your Certificado Digital from the list of installed certificates, confirm the signature, and the signed document is returned to the portal. The entire process takes a few seconds once everything is set up.
What goes wrong
The most common problem is browser compatibility. Autofirma works best with Google Chrome and Mozilla Firefox. Safari on macOS can have issues with the signing integration. Microsoft Edge usually works but sometimes requires additional configuration. If the portal asks you to sign and nothing happens, try switching browsers before troubleshooting further.
The second common problem is certificate recognition. If Autofirma does not show your Certificado Digital when you try to sign, the certificate may not be properly installed in your browser's certificate store. On Windows, the certificate needs to be in the Windows Certificate Store. On macOS, it needs to be in the Keychain. Reinstalling the certificate usually resolves the issue.
The third issue is Java. Autofirma historically depended on Java, and some older versions still require it. Current versions (2024 and later) have reduced this dependency, but if you encounter Java related errors, installing the latest version of Java from java.com may help.
Autofirma on mobile
There is a mobile version of Autofirma available for Android and iOS. It allows you to sign documents on your phone using a Certificado Digital stored on your device. However, the mobile experience is less reliable than the desktop version, and most government portals are optimised for desktop browsers. For important submissions (tax returns, visa applications), we recommend using the desktop version.
