Signing a Facturae file: certificate, XAdES format and steps
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Choose what you are signing: the calculator tells you which signature the rules require, whether signing is needed and who signs, for Facturae, B2B invoices or Verifactu records.
Signature required
XAdES
Advanced electronic signature based on a qualified certificate, or an electronic seal (Law 25/2013, art. 5).
| Rule | Ley 25/2013 |
| Who signs | The issuer or whoever invoices on its behalf |
No tool on this site signs: you sign with your certificate on your own device.
Prepared by Radif Partners · Method · Rules read in the BOE and at the AEAT on 25 October 2026
An invoice to a Spanish public body only counts if it is signed. Article 5 of Law 25/2013 requires e-invoices sent to public bodies to carry an advanced electronic signature based on a qualified certificate, or an advanced electronic seal of the entity identifying its name and tax ID. In Facturae the signature sits inside the XML file itself, in XAdES format, and follows the signature policy published on facturae.gob.es, currently version 3.1. Companies usually sign with a legal representative certificate and the self-employed with their personal certificate, using a signing application installed on their computer. No website can sign for you without accessing your certificate, which is why the creator on this site delivers the XML unsigned. Signing is not only a FACe matter: B2B invoices carried by private platforms will also bear an advanced signature, and under Verifactu, software that does not send records to the Tax Agency must sign each record in XAdES Enveloped (ETSI EN 319 132) format.
Which signature each case needs
| What you sign | Signature required | Rule |
|---|---|---|
| Facturae for a public body | Advanced with qualified certificate, or advanced electronic seal | Law 25/2013, art. 5 |
| B2B invoice via private platform | Advanced, by the issuer or delegated | RD 238/2026, art. 7.3 |
| B2B invoice via the public solution | Ensured by AEAT procedures | RD 238/2026, art. 11.7 |
| VERI*FACTU record | Not signed: sent to the AEAT | RD 1007/2023, art. 16 |
| Non-VERI*FACTU record | XAdES Enveloped (ETSI EN 319 132) | Order HAC/1177/2024, art. 14 |
Law 25/2013 only asks for an advanced signature based on a qualified certificate, but Facturae spells out how: the signature is embedded in the XML following the Facturae signature policy, version 3.1, which sets the algorithms and properties it must carry. That is why a signed PDF is no substitute for Facturae: what gets signed is the structured file.
How to sign, step by step
First, produce the unsigned XML with your software, the official application or the Facturae creator on this site. Second, check that every detail is correct, because after signing you cannot change anything. Third, open the file in a signing application that supports XAdES, such as the signing application offered by the Spanish administration, choose your certificate and save the result, which usually has the .xsig extension. Finally, file it in FACe or the relevant entry point, as explained on FACe.
Signing B2B invoices depends on the channel. Article 7 of Royal Decree 238/2026 requires an advanced signature on every invoice issued through a private platform, while on the Tax Agency public solution integrity is ensured by the Agency's own procedures. Check which format and signature apply to each destination:
Format and signature
Format and signature
UBL, CII, EDIFACT, Facturae
| Mandatory since | 6 October 2027 / 6 October 2028 |
| Unique identifier | Tax ID + series and number + date |
| Statuses | Acceptance, rejection and payment in 4 days |
Signatures under Verifactu
Verifactu has a signature too, but for records, not for the invoice. Under Royal Decree 1007/2023, systems that send each record to the Tax Agency do not need to sign them. Systems that keep records instead, the non-VERI*FACTU mode, sign each one with a qualified certificate in XAdES Enveloped (ETSI EN 319 132) format, under article 14 of Order HAC/1177/2024. The differences between the two modes are on VERI*FACTU or non-VERI*FACTU. If your software works in this second mode, the certificate it uses to sign records can be the same one you use for your Facturae files, so keep an eye on its expiry date: once it lapses, both the invoices and the records stop being signed correctly.