UBL-SR-04
EN 16931-1 layer: en16931
Checked against Peppol BIS Billing 3.0 2026.5
What does UBL-SR-04 mean? Invoice object identifier shall occur maximum once
Why did my invoice fail UBL-SR-04?
The Invoice object identifier (BT-18), an identifier for a referenced object such as a business object the invoice relates to, may occur at most once. In UBL it is carried in cac:AdditionalDocumentReference where cbc:DocumentTypeCode equals '130', and only one such reference of that type is permitted.
Official rule text
Invoice object identifier shall occur maximum once
Common causes
- Multiple cac:AdditionalDocumentReference blocks are given DocumentTypeCode '130' when only one is the object identifier.
- Object reference is duplicated alongside an attachment reference sharing the same type code.
- Loop over related objects emits several object-identifier references.
How do I fix it?
Provide exactly one: <cac:AdditionalDocumentReference><cbc:ID schemeID="...">OBJ-123</cbc:ID><cbc:DocumentTypeCode>130</cbc:DocumentTypeCode></cac:AdditionalDocumentReference> and change or remove other references using code 130.
Related rules
UBL-SR-01 · UBL-SR-02 · UBL-SR-03 · UBL-SR-05 · UBL-SR-06 · UBL-SR-07 · UBL-SR-08 · UBL-SR-09
Check your invoice against this rule
Paste it into the live demo, or call POST /v1/validate. See the quickstart.