UBL-CR-594: Remove CommodityCode from the item classification

The short answer

UBL-CR-594 is a warning raised when cbc:CommodityCode appears in the item classification (cac:InvoiceLine/cac:Item/cac:CommodityClassification). EN 16931 has no business term for it, so remove the element. Classify the item with cbc:ItemClassificationCode and its listID (BT-158).

The warning on its own does not make the document invalid, though other rules still check what is there. Removing the element keeps the XML inside the EN 16931 model, which is what a receiver maps the invoice from.

What the rule checks

The rule checks one thing: whether cac:InvoiceLine/cac:Item/cac:CommodityClassification/cbc:CommodityCode exists. Its value is not read.

It runs once against the whole document, so it is reported once however many lines carry the element, and the finding points at the document root rather than at the element: look for cac:InvoiceLine/cac:Item/cac:CommodityClassification/cbc:CommodityCode in the XML.

How an integration ends up here

Possible causes, from the shape of the rule rather than from measured usage:

• The source system holds the value, and the mapping writes it because UBL 2.1 has a place for it.
• A general UBL 2.1 library writes every element and attribute it has a value for, whether or not EN 16931 uses it.
• A mapping built for another UBL-based document, such as an order, a despatch advice or a national profile, is reused for Peppol BIS Billing.

How to fix it

1. Stop writing cac:InvoiceLine/cac:Item/cac:CommodityClassification/cbc:CommodityCode.
2. Classify the item with cbc:ItemClassificationCode and its listID (BT-158).
3. Validate again: the warning goes. If the element was the only thing in its parent, remove the parent too: Peppol refuses empty elements (PEPPOL-EN16931-R008).

Validate your corrected invoice

Before and after

These are fragments, not complete documents. The complete synthetic documents they come from are linked below.

Fragment of the invoice with the warning: CommodityCode in the item classification

<cac:CommodityClassification>
  <cbc:CommodityCode>EXAMPLE</cbc:CommodityCode>
  <cbc:ItemClassificationCode listID="STI">30192000</cbc:ItemClassificationCode>
</cac:CommodityClassification>

Fragment of the corrected invoice: the same lines without it

<cac:CommodityClassification>
  <cbc:ItemClassificationCode listID="STI">30192000</cbc:ItemClassificationCode>
</cac:CommodityClassification>

The invoice with the warning has <cbc:CommodityCode>EXAMPLE</cbc:CommodityCode> in the item classification, and the corrected invoice is the same document without it. It reports only this warning and is valid on every layer, so it would be accepted as it stands.

Where it applies

• Applies to UBL Invoice and CreditNote alike, on invoice lines and credit note lines; the recorded example is an invoice.
• The warning comes from the EN 16931 layer's rules for the UBL syntax. In the recorded example the schema layer passes: the element is valid UBL 2.1 and is only outside the EN 16931 model.

Related rules

• UBL-CR-592: NatureCode in the item classification
• UBL-CR-593: CargoTypeCode in the item classification
• Browse every rule in the reference
• Background: Understanding EN 16931 validation errors

Scope and source

Written for Peppol BIS Billing 3.0.21 (May 2026), EN 16931 1.3.16, as applied to UBL 2.1 Invoice and CreditNote documents. Other profiles, syntaxes and releases can define this identifier differently. Guidance version 2026-09-29.1: source checked 2026-09-29, explanation last updated 2026-09-29.

The official definition of UBL-CR-594 carries the normative wording and test. This page is our explanation of it, not a copy.

Guidance does not change the engine verdict. Fixing this finding does not mean the document passes every layer, and validation does not certify legal or tax compliance or transmit a document over Peppol.