UBL-SR-01
EN 16931-1 layer: en16931
Checked against Peppol BIS Billing 3.0 2026.5
What does UBL-SR-01 mean? Contract identifier shall occur maximum once.
Why did my invoice fail UBL-SR-01?
The Contract reference identifier (BT-12) may occur at most once on the invoice, so only a single cac:ContractDocumentReference is allowed at document level. EN 16931 defines the contract reference as a single-cardinality business term identifying the underlying contract.
Official rule text
Contract identifier shall occur maximum once.
Common causes
- Two or more cac:ContractDocumentReference elements appear on the invoice.
- Contract numbers from multiple related agreements were all mapped to ContractDocumentReference.
- A duplicate contract reference was emitted during document assembly or merging.
How do I fix it?
Keep exactly one: <cac:ContractDocumentReference><cbc:ID>CONTRACT-2026-88</cbc:ID></cac:ContractDocumentReference> and remove additional occurrences.
Related rules
UBL-SR-02 · UBL-SR-03 · UBL-SR-04 · UBL-SR-05 · UBL-SR-06 · UBL-SR-07 · UBL-SR-08 · UBL-SR-09
Check your invoice against this rule
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