Validation rules

BR-31

A document-level allowance (BG-20) has no allowance amount (BT-92).

Rule

BR-31 — official EN 16931 / XRechnung rule

Severity

error

Business term

BT-92 — Document allowance amount

Field in your JSON

invoice.allowances[*].amount

Detected by

tier 3 — KoSIT validator (authoritative)

Reachability

Only reachable when validating your own XML — normbill-generated documents cannot trigger it

The request schema requires amount (or base_amount + percent) on every allowance and the serializer always writes cbc:Amount; the UBL schema makes the element mandatory too, so the XSD tier reports hand-built XML without it first.

How to fix it

Add cbc:Amount to the allowance.

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.