Validation rules

BR-51 — EN 16931 rule

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.

Related rules

BR-50 — A credit-transfer payment account is present but its account identifier (IBAN, BT-84) is empty.
BR-52 — An additional supporting document (BG-24) has no document reference (BT-122).
BR-49 — Payment instructions (BG-16) are present but the payment means type code (BT-81) is missing.
BR-53 — A VAT accounting currency (BT-6) is given, so the VAT total in that currency (BT-111) must be present as well.
BR-48 — A VAT breakdown (BG-23) has no VAT category rate (BT-119); only category O (not subject to VAT) may omit it.
BR-54 — An item attribute (BG-32) must carry both a name (BT-160) and a value (BT-161).

Official sources

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.

Or try it live: drop any XRechnung XML on the free validator — same KoSIT-backed report, no account.