Validation rules

BR-CO-21

A document-level allowance (BG-20) carries neither a reason text (BT-97) nor a reason code (BT-98) — at least one is required.

Rule: BR-CO-21 — official EN 16931 / XRechnung rule
Severity: error
Business term: BT-97 — Document allowance reason
Field in your JSON: invoice.allowances[*].reason
Detected by: tier 1 — normbill pre-flight (also in the playground)
Reachability: Triggerable from your request JSON (generate & validate)

normbill's pre-flight reports the equivalent finding as BR-33 at tier 1, before the KoSIT validator sees the document.

How to fix it

Set the allowance's reason (e.g. "Rabatt") or a UNCL 5189 reason_code.

BR-CO-21 auf Deutsch — was bedeutet der Fehler?

Ein Nachlass auf Dokumentebene (BG-20) trägt weder einen Grundtext (BT-97) noch einen Grundcode (BT-98) — mindestens eines ist Pflicht.

So beheben Sie den Fehler

Setzen Sie reason des Nachlasses (z. B. "Rabatt") oder einen UNCL-5189-reason_code. normbill meldet denselben Befund bereits vorab als BR-33.

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.