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

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.