XRechnung BR-DE-21: specification identifier is not XRechnung
BR-DE-21 is a warning: the specification identifier (BT-24, CustomizationID) should syntactically correspond to the official identifier of the XRechnung standard (e.g. 'urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0').
Last updated: 2026-06-01
Affected field
cbc:CustomizationID (BT-24, UBL) / ram:GuidelineSpecifiedDocumentContextParameter/ram:ID (CII)
Cause
The CustomizationID is missing, outdated, or points to a different CIUS/specification than XRechnung. Common with tools that emit only 'urn:cen.eu:en16931:2017' (the EN 16931 core).
Fix
Set the CustomizationID to the valid XRechnung identifier, e.g. 'urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0'. The exact string is published in the KoSIT specification for your XRechnung version.
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Frequently asked questions
Is BR-DE-21 a hard error?▼
No, it is a 'should' rule (warning). But an incorrect or missing XRechnung identifier can cause downstream systems to fail to recognise the document as an XRechnung.
How does BR-DE-21 differ from BR-1?▼
BR-1 (EN 16931) requires that a specification identifier (BT-24) is present at all. BR-DE-21 additionally requires that identifier to be the XRechnung one.