Validation rules

BR-52

An additional supporting document (BG-24) has no document reference (BT-122).

Rule: BR-52 — official EN 16931 / XRechnung rule
Severity: error
Business term: BT-122 — Supporting document reference
Field in your JSON: invoice.supporting_documents[*].id
Detected by: tier 3 — KoSIT validator (authoritative)
Reachability: Not expressible through the normbill invoice model — documented for completeness

The request schema requires supporting_documents[i].id (BT-122); generated XML always writes cbc:ID.

How to fix it

Add cbc:ID to every cac:AdditionalDocumentReference.

BR-52 auf Deutsch — was bedeutet der Fehler?

Eine rechnungsbegründende Unterlage (BG-24) hat keine Dokumentenreferenz (BT-122).

So beheben Sie den Fehler

Ergänzen Sie cbc:ID in jeder cac:AdditionalDocumentReference.

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.