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BR-02: Invoice number (BT-1) is missing

Official message

[BR-02] An Invoice shall have an Invoice number (BT-1).

EN 16931 (CII) · Error · Message language: English · Version: xrechnung-3.0.2-validator-configuration-2026-08-31

[BR-02] An Invoice shall have an Invoice number (BT-1).

EN 16931 (UBL) · Error · Message language: English · Version: xrechnung-3.0.2-validator-configuration-2026-08-31

[BR-02] An Invoice shall have an Invoice number (BT-1).

Factur-X / ZUGFeRD EN 16931 · Error · Message language: English · Version: Factur-X 1.08 / ZUGFeRD 2.4
Severity
Error The invoice is invalid and may be rejected by the recipient.
Applies to
EN 16931 (CII), EN 16931 (UBL), Factur-X / ZUGFeRD EN 16931
Affected fields
BT-1

What does this mean?

Every invoice must have an invoice number (BT-1) that uniquely identifies it. The element is missing or contains only spaces.

Typical causes

No invoice number was assigned, e.g. for a draft exported before numbering.
The element exists but is empty.

How to fix the error

Assign and enter a unique invoice number.
CII: rsm:ExchangedDocument/ram:ID, UBL: cbc:ID.
Generate and validate the invoice again.

In E-Rechnungsfreund

In the invoice form, section "Rechnungsdetails" (invoice details), fill in the field "Rechnungsnummer (BT-1)" (invoice number).

Example

Wrong

<rsm:ExchangedDocument>
  <ram:ID></ram:ID>
  <ram:TypeCode>380</ram:TypeCode>
  ...
</rsm:ExchangedDocument>

Correct

<rsm:ExchangedDocument>
  <ram:ID>INV-2026-0042</ram:ID>
  <ram:TypeCode>380</ram:TypeCode>
  ...
</rsm:ExchangedDocument>
For developers: test expression per syntax

EN 16931 (CII) (CII)

Context: /rsm:CrossIndustryInvoice

normalize-space(rsm:ExchangedDocument/ram:ID) != ''

EN 16931 (UBL) (UBL)

Context: /ubl:Invoice | /cn:CreditNote

normalize-space(cbc:ID) != ''

Factur-X / ZUGFeRD EN 16931 (CII)

Technical ID in the source: FX-SCH-A-000011

Context: /rsm:CrossIndustryInvoice

(rsm:ExchangedDocument/ram:ID !='')

Related validation rules

  • BR-01: Specification identifier (BT-24) is missing
  • BR-03: Invoice issue date (BT-2) is missing
  • BR-04: Invoice type code (BT-3) is missing
  • BR-05: Invoice currency code (BT-5) is missing
  • BR-06: Seller name (BT-27) is missing
  • BR-07: Buyer name (BT-44) is missing

Last updated:
Explanation of the validation rule, not legal or tax advice.