Validation rules

UBL-SR-06 — UBL rule

A cac:BillingReference contains more than one cac:InvoiceDocumentReference — each preceding-invoice reference (BG-3) holds exactly one.

Rule: UBL-SR-06 — official EN 16931 / XRechnung rule
Severity: error
Detected by: tier 3 — KoSIT validator (authoritative)
Reachability: Only reachable when validating your own XML — normbill-generated documents cannot trigger it

The serializer emits one BillingReference with exactly one InvoiceDocumentReference for invoice.preceding_invoice.

How to fix it

Use one cac:BillingReference per preceding invoice, each with a single InvoiceDocumentReference.

UBL-SR-06 auf Deutsch — was bedeutet der Fehler?

Der KoSIT-Validator lehnt die Rechnung ab, weil eine cac:BillingReference mehr als eine cac:InvoiceDocumentReference enthält — jede Referenz auf eine Vorgängerrechnung (BG-3) enthält genau eine.

So beheben Sie den Fehler

Verwenden Sie pro Vorgängerrechnung eine eigene cac:BillingReference mit jeweils einer InvoiceDocumentReference.

Related rules

UBL-SR-05 — Payment terms (BT-20) appear more than once — across all cac:PaymentTerms elements only a single cbc:Note is…
UBL-SR-07 — A cac:BillingReference is present but the preceding invoice number (BT-25, InvoiceDocumentReference/cbc:ID)…
UBL-SR-04 — The invoiced-object identifier (BT-18) appears more than once — only one cac:AdditionalDocumentReference…
UBL-SR-08 — The invoicing period (BG-14) appears more than once — only one document-level cac:InvoicePeriod is allowed.
UBL-SR-03 — The despatch advice reference (BT-16) appears more than once — only one cac:DespatchDocumentReference with…
UBL-SR-09 — The seller name (BT-27) appears more than once — the supplier party may carry only one…

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.