BR-01

The invoice must carry a specification identifier (BT-24), which tells the recipient which rule set the invoice was built against.

Severity: Error
Applies to: CII, UBL
Rule set: v2026-01-31

Official rule text

An Invoice shall have a Specification identifier (BT-24).

Why it happens

Commonly forgotten, or inherited from an older template that still points at a previous XRechnung version.

How to fix it

Set BT-24 to the identifier of the XRechnung version you are producing — cbc:CustomizationID in UBL, ram:GuidelineSpecifiedDocumentContextParameter/ram:ID in CII.

NormAPI provides technical validation, not tax or legal advice.