Validation rules

UBL-SR-21 — UBL rule

The payee legal registration identifier (BT-61) is invalid: at most one PartyLegalEntity/CompanyID is allowed in cac:PayeeParty, and the payee must differ from the seller.

Rule: UBL-SR-21 — 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 normbill invoice model has no payee party (BG-10); generated XML never contains cac:PayeeParty.

How to fix it

Keep a single payee CompanyID, or remove the PayeeParty when the seller is paid directly.

UBL-SR-21 auf Deutsch — was bedeutet der Fehler?

Der KoSIT-Validator lehnt die Rechnung ab: die Registernummer des Zahlungsempfängers (BT-61) darf höchstens einmal vorkommen, und der Zahlungsempfänger muss sich vom Verkäufer unterscheiden.

So beheben Sie den Fehler

Behalten Sie genau eine CompanyID beim Zahlungsempfänger — oder entfernen Sie die PayeeParty.

Related rules

UBL-SR-20 — The payee identifier (BT-60) is invalid: cac:PayeeParty may carry at most one PartyIdentification/ID (SEPA…
UBL-SR-22 — The tax representative name (BT-62) appears more than once — cac:TaxRepresentativeParty may carry only one…
UBL-SR-19 — The payee name (BT-59) is invalid: cac:PayeeParty may carry at most one PartyName/Name, and it must differ…
UBL-SR-23 — The tax representative VAT identifier (BT-63) appears more than once — only one PartyTaxScheme/CompanyID is…
UBL-SR-18 — The buyer VAT identifier (BT-48) appears more than once — only one PartyTaxScheme with TaxScheme/ID 'VAT'…
UBL-SR-24 — Delivery information (BG-13) appears more than once — only one cac:Delivery element is allowed.

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.