PEPPOL-EN16931-R003: Neither buyer reference nor purchase order reference given

StandardPeppol BIS Billing 3.0 (OpenPeppol)SeverityError: the invoice is rejectedSyntaxUBL, CIIApplies toInvoices and credit notes sent over the Peppol network (UBL) and, because XRechnung embeds the Peppol rule set, every XRechnung as well.

Official rule text

[PEPPOL-EN16931-R003] A buyer reference or purchase order reference MUST be provided.

Why this error occurs

Peppol BIS requires a buyer reference (BT-10) or a purchase order reference (BT-13) so the buyer's system can match the invoice automatically. The rule checks cbc:BuyerReference or cac:OrderReference/cbc:ID (UBL), ram:BuyerReference or ram:BuyerOrderReferencedDocument/ram:IssuerAssignedID (CII). It fails when the order number is only printed in the line text or when the customer record carries no reference.

How to fix it

Add cbc:BuyerReference (UBL) / ram:BuyerReference in ram:ApplicableHeaderTradeAgreement (CII) with the reference the buyer gave you (cost centre, contact, Leitweg-ID), or add cac:OrderReference/cbc:ID (UBL) / ram:BuyerOrderReferencedDocument/ram:IssuerAssignedID (CII) with the buyer's purchase order number. If neither is known, ask the buyer; as a fallback many senders repeat the buyer's customer number in cbc:BuyerReference. In UBL cbc:BuyerReference precedes cac:OrderReference in element order.

Example (valid)

<cbc:BuyerReference>PO-55821</cbc:BuyerReference>
<cac:OrderReference>
  <cbc:ID>PO-55821</cbc:ID>
</cac:OrderReference>

What the validator checks

Checked element (context):

UBL

ubl-creditnote:CreditNote | ubl-invoice:Invoice

Test (XPath):

cbc:BuyerReference or cac:OrderReference/cbc:ID

CII

ram:ApplicableHeaderTradeAgreement

Test (XPath):

ram:BuyerReference or ram:BuyerOrderReferencedDocument/ram:IssuerAssignedID

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Related rules

PEPPOL-EN16931-R001 Business process identifier (BT-23) is missing
PEPPOL-EN16931-R002 No more than one note is allowed on document level, unless both the buyer and seller…
PEPPOL-EN16931-R004 Specification identifier is not the Peppol BIS Billing 3.0 identifier
PEPPOL-EN16931-R005 VAT accounting currency equals the invoice currency
PEPPOL-EN16931-R006 Only one invoiced object is allowed on document level
PEPPOL-EN16931-R007 Business process identifier has the wrong format
PEPPOL-EN16931-R008 Document contains empty elements
PEPPOL-EN16931-R010 Buyer electronic address (BT-49) is missing

Frequently asked questions

What does PEPPOL-EN16931-R003 mean?

PEPPOL-EN16931-R003 is a peppol bis billing 3.0 rule: A buyer reference or purchase order reference MUST be provided.

Will my invoice be rejected because of PEPPOL-EN16931-R003?

Yes. PEPPOL-EN16931-R003 is flagged "fatal"; validators (KoSIT, Peppol access points, the German ZRE/OZG-RE portals) reject the invoice until it is fixed.

Which formats does PEPPOL-EN16931-R003 apply to?

Invoices and credit notes sent over the Peppol network (UBL) and, because XRechnung embeds the Peppol rule set, every XRechnung as well. Syntax: UBL and CII.

Source: Peppol BIS Billing 3.0.20 (November 2025). Catalogue generated from the official schematron on 2026-10-14.