Electronic signature looks suspicious
The file is electronically signed, but the signature is damaged or could not be fully verified. This may mean that the file was changed after it was signed.
What to do now
Who has to fix this?
The issuer of the invoice has to fix this. In the case of an invalid IBAN or an arithmetic error, you as the recipient should ask before paying.
Where this rule comes from
Billvox runs these checks in addition to the official rule sets — for every format, including those without a rule set of their own. They check whether the most important details are present, whether IBAN and VAT IDs have a plausible structure, whether the amounts add up and whether the file matches the schema (XSD) of its format. The abbreviations BT and BG denote the fields and field groups of EN 16931.
- Rule ID
- SIGNATUR
- Rule set
- Additional checks by Billvox
- Checked for
- XRechnung, ZUGFeRD, Factur-X, Peppol BIS and other EN 16931 formats
- Consequence of a violation
- A notice from Billvox's additional checks. Whether the recipient accepts the invoice depends on their own validation system.
Does SIGNATUR occur in your invoice?
Upload the XRechnung or the ZUGFeRD/Factur-X PDF – the validator shows every violation with the same explanation as here. Free, no login, nothing stored.
Validate your invoice nowGeneral information, not tax or legal advice. As of October 2026. Validation rules: CEN/TC 434 (EN 16931, EUPL 1.2), KoSIT (XRechnung, Apache 2.0), FNFE-MPE/FeRD (Factur-X/ZUGFeRD, Apache 2.0), OpenPeppol AISBL (Peppol BIS), ANAF (CIUS-RO). Explanations: Billvox. Licence notices