Do I need BOTH BuyerReference and OrderReference?

No. R003 is satisfied if either one is present with a non-empty value. Providing both is allowed and improves invoice matching on the buyer side, but it is not required.

What is a Leitweg-ID and where does it go?

The Leitweg-ID is the routing identifier for German public sector invoicing. It goes in cbc:BuyerReference (BT-10). Without it, the invoice cannot be routed through the ZRE or OZG-RE portal.

Can I put a placeholder like N/A in BuyerReference?

Technically it passes R003, but it is a bad practice. Ask the buyer for a real reference — otherwise the invoice will fail to auto-match on their side and cause payment delays.

What if my invoice has no PO because the customer paid up front?

Populate cbc:BuyerReference with your own internal identifier (quote number, contract reference, or the customer's cost centre if known). This satisfies R003 and helps reconciliation.

Can Invoice Navigator auto-fix R003?

No — this requires input. Invoice Navigator flags R003 and prompts for a value; if you configure a standing rule (e.g. always use quote number), it applies automatically to future invoices.

Error codes · EN 16931

PEPPOL-EN16931-R003Fixable here

Buyer reference or order reference is required

This is the rejection, word for word: „[PEPPOL-EN16931-R003] PEPPOL-EN16931-R003 fires when a Peppol invoice contains neither a buyer reference (BT-10, cbc:BuyerReference) nor an order reference (BT-13, cac:OrderReference/cbc:ID). At least one of the two must be present. This lets the buyer's AP process (Accounts Payable) match the incoming invoice to their internal purchase order or cost centre without manual research.“

The Schematron rule PEPPOL-EN16931-R003 asserts that /Invoice/cbc:BuyerReference OR /Invoice/cac:OrderReference/cbc:ID must exist and be non-empty. It is an OR — you only need one. cbc:BuyerReference is a free-text field (often the buyer's cost centre or Leitweg-ID for German public bodies). cac:OrderReference/cbc:ID is the buyer's purchase order number. Providing an empty element for either counts as absent under PEPPOL-EN16931-R008.

What to have readyBuyer Reference / PO Number

What we doPopulate cbc:BuyerReference with the buyer's reference (cost centre, Leitweg-ID, or agreed identifier), OR populate cac:OrderReference/cbc:ID with the purchase order number. This requires input — the value must come from the buyer.

Choose the rejected invoiceor drop it here

XRechnung XML or ZUGFeRD PDF. Checking is free · corrected file €1.90 · the first every 30 days is free · no sign-up.

If you enter it yourself in your invoicing software

Before

<Invoice xmlns="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2">
  <cbc:ID>INV-2026-0842</cbc:ID>
  <cbc:IssueDate>2026-08-12</cbc:IssueDate>
  <cbc:InvoiceTypeCode>380</cbc:InvoiceTypeCode>
  <!-- neither cbc:BuyerReference nor cac:OrderReference present -->
  <cbc:DocumentCurrencyCode>EUR</cbc:DocumentCurrencyCode>
</Invoice>

After

<Invoice xmlns="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2">
  <cbc:ID>INV-2026-0842</cbc:ID>
  <cbc:IssueDate>2026-08-12</cbc:IssueDate>
  <cbc:InvoiceTypeCode>380</cbc:InvoiceTypeCode>
  <cbc:BuyerReference>04011000-1234512345-06</cbc:BuyerReference>
  <cbc:DocumentCurrencyCode>EUR</cbc:DocumentCurrencyCode>
  <cac:OrderReference>
    <cbc:ID>PO-2026-000442</cbc:ID>
  </cac:OrderReference>
</Invoice>

What the finding looks likeExample

FindingValue missing · PEPPOL-EN16931-R003

Location/Invoice/cbc:BuyerReference

From youBuyer Reference / PO Number

ThenPassed

ProofSHA-256 and /verify link after the check