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Compliant e-invoices in one POST request. Generate, validate and parse XRechnung and ZUGFeRD / Factur-X. Made in Germany, hosted in the EU.

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© 2026 VIBOA UG (haftungsbeschränkt) · HannoverDE · EN

Not legal or tax advice. XRechnung® is a standard of KoSIT; ZUGFeRD® of FeRD. Names used for format identification only.

DocumentationAuthenticationYour first invoiceThe 422 reportQuotas & limitsTest vs. live keys
API referencePOST…/generatePOST…/validatePOST…/parse
ReferenceError codesValidation rulesInteractive referenceOpenAPI spec↗@normbill/xrechnung↗Status

Validation rules

BR-51

A card payment must never carry the full primary account number (BT-87) — at most the first 6 and last 4 digits are allowed.

Rule
BR-51 — official EN 16931 / XRechnung rule
Severity
error
Business term
BT-87
Detected by
tier 3 — KoSIT validator (authoritative)
Reachability
Not expressible through the normbill invoice model — documented for completeness

The normbill invoice model has no card payment information (BG-18).

How to fix it

Truncate the card number in cac:CardAccount/cbc:PrimaryAccountNumberID.

BR-51 auf Deutsch — was bedeutet der Fehler?

Bei Kartenzahlung darf niemals die vollständige Kartennummer (BT-87) übertragen werden — höchstens die ersten 6 und letzten 4 Ziffern.

So beheben Sie den Fehler

Kürzen Sie die Kartennummer in cac:CardAccount/cbc:PrimaryAccountNumberID.

Official sources

  • XRechnung specification (KoSIT / xeinkauf.de)
  • KoSIT validator on GitHub and the XRechnung validator configuration

Every 422 from the API lists the rule id, the path in your request JSON, a plain-language message and a suggested fix — see the docs overview for the report format.