Validation rules
UBL-SR-28
The direct-debit mandate reference (BT-89) appears more than once — only one PaymentMandate/cbc:ID per cac:PaymentMeans is allowed.
- Rule
UBL-SR-28— 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 at most one PaymentMandate/cbc:ID, from invoice.payment.mandate_id.
How to fix it
Keep a single mandate reference per payment means.
UBL-SR-28 auf Deutsch — was bedeutet der Fehler?
Der KoSIT-Validator lehnt die Rechnung ab, weil die Mandatsreferenz (BT-89) mehrfach vorkommt — nur eine PaymentMandate/cbc:ID je cac:PaymentMeans ist erlaubt.
So beheben Sie den Fehler
Behalten Sie genau eine Mandatsreferenz je Zahlungsweg.
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.