BR – Core rules of EN 16931

BR-01: specification identifier (BT-24) missing

ErrorEN 16931 business rule (CEN)

Official message

[BR-01]-An Invoice shall have a Specification identifier (BT-24).

Source: CEN EN 16931, version 1.3.16

What the message means

The invoice does not say which specification it was built for. That identifier is the first value a recipient reads: it decides whether the file is checked as an XRechnung, a Peppol invoice or a plain EN 16931 invoice. When it is missing or empty, no validation system can pick the right rules and the invoice is rejected.

How to fix it

Put the specification identifier into CustomizationID (UBL) or GuidelineSpecifiedDocumentContextParameter/ID (CII), for example the XRechnung identifier or urn:cen.eu:en16931:2017 for a plain EN 16931 invoice.

Before – invalid

<ubl:Invoice>
  <cbc:ID>RE-2026-0142</cbc:ID>
  <cbc:IssueDate>2026-09-01</cbc:IssueDate>
</ubl:Invoice>

After – corrected

<ubl:Invoice>
  <cbc:CustomizationID>urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0</cbc:CustomizationID>
  <cbc:ID>RE-2026-0142</cbc:ID>
  <cbc:IssueDate>2026-09-01</cbc:IssueDate>
</ubl:Invoice>

Frequently asked

Which identifier do I use for an invoice to a German public body?

The XRechnung identifier urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0. For Peppol recipients the Peppol BIS identifier, for everyone else the plain EN 16931 identifier.

Where does the specification identifier go in the CII format?

Under rsm:ExchangedDocumentContext/ram:GuidelineSpecifiedDocumentContextParameter/ram:ID, right at the start of the file.

Also seen when …

The invoicing software writes no CustomizationID because the invoice type is not configured.
The field holds only spaces or a placeholder that comes out empty in the export.
The ExchangedDocumentContext element was lost when converting from another format.

Fields concerned

BT-24

Related rules

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Technical details

UBL · Context (XPath): /ubl:Invoice | /cn:CreditNote
UBL · Schematron test: normalize-space(cbc:CustomizationID) != ''
CII · Context (XPath): /rsm:CrossIndustryInvoice
CII · Schematron test: normalize-space(rsm:ExchangedDocumentContext/ram:GuidelineSpecifiedDocumentContextParameter/ram:ID) != ''

Explanation written on 13 September 2026