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Warning

UBL-CR-028: Do not send an XPath in the earlier invoice reference

In short

Warning: worth checking.

UBL-CR-028 warns that your UBL invoice or credit note contains an XPath (cbc:XPath) in its reference to an earlier invoice. Remove that element from cac:BillingReference/cac:InvoiceDocumentReference.

On this page

What it means

When an invoice or credit note refers to an earlier invoice, EN 16931 carries only that invoice's number (BT-25) and date (BT-26), in cac:BillingReference/cac:InvoiceDocumentReference. This rule checks that the reference does not also contain cbc:XPath, a technical path into the earlier document.

Why it matters

The EN 16931 UBL rules do not use an XPath in the reference to an earlier invoice.

How to fix it

Remove only cbc:XPath from cac:BillingReference/cac:InvoiceDocumentReference. Keep the earlier invoice number (BT-25) in cbc:ID and any existing invoice date (BT-26) in cbc:IssueDate. Check the corrected file again.

Once the file is corrected, check it again for free: Validate an invoice against EN 16931

Or fix the invoice in a form and download the corrected file, for 1 credit: Fix a rejected e-invoice

The rule as published

A UBL invoice should not include the BillingReference Xpath

Where this rule applies

Rule set Version
EN 16931 (UBL) 1.3.17
EN 16931 (UBL credit note) 1.3.17
XRechnung 3.0 (UBL) 3.0.2
XRechnung 3.0 (UBL credit note) 3.0.2
Peppol BIS Billing 3.0 (invoice) 2026.5
Peppol BIS Billing 3.0 (credit note) 2026.5
SI-UBL 2.0 / NLCIUS (invoice) 2.0.3.13
SI-UBL 2.0 / NLCIUS (credit note) 2.0.3.13
France CTC (UBL invoice) 1.4.0-04
France CTC (UBL credit note) 1.4.0-04
CIUS-RO UBL Invoice 1.0.9 1.0.9
CIUS-RO UBL Credit Note 1.0.9 1.0.9
Rule text from phive-rules 4.6.4.

Check your file

Drop your e-invoice to see whether UBL-CR-028 still fails, and which other rules do.

Updated 6 November 2026