Validation rules

BR-55 — EN 16931 rule

A preceding-invoice reference (BG-3) is present but the preceding invoice number (BT-25) is missing.

Rule: BR-55 — official EN 16931 / XRechnung rule
Severity: error
Business term: BT-25 — Preceding invoice number
Field in your JSON: invoice.preceding_invoice
Detected by: tier 3 — KoSIT validator (authoritative)
Reachability: Only reachable when validating your own XML — normbill-generated documents cannot trigger it

The serializer only writes cac:BillingReference when invoice.preceding_invoice is set (non-empty).

How to fix it

Add cac:InvoiceDocumentReference/cbc:ID to the cac:BillingReference.

BR-55 auf Deutsch — was bedeutet der Fehler?

Eine Referenz auf eine Vorgängerrechnung (BG-3) ist vorhanden, aber die Nummer der Vorgängerrechnung (BT-25) fehlt.

So beheben Sie den Fehler

Ergänzen Sie cac:InvoiceDocumentReference/cbc:ID in der cac:BillingReference.

Related rules

BR-DE-26 — A corrected invoice (type_code 384) should reference the invoice it corrects (BT-25).
UBL-SR-07 — A cac:BillingReference is present but the preceding invoice number (BT-25, InvoiceDocumentReference/cbc:ID)…
BR-54 — An item attribute (BG-32) must carry both a name (BT-160) and a value (BT-161).
BR-56 — A seller tax representative (BG-11) must carry the representative's VAT identifier (BT-63).
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-57 — A deliver-to address (BG-15) must contain a country code (BT-80).

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.