BR-DE-15 — BuyerReference (Leitweg-ID) is missing
What it means
XRechnung requires the BuyerReference field (BT-10) on every invoice. For German public-sector buyers (B2G) this must be the Leitweg-ID — the routing identifier that tells the German government network which authority receives your invoice. Without it, the invoice is rejected before anyone reads it.
What triggers it
Your invoice has no BuyerReference element (UBL cbc:BuyerReference / CII ram:BuyerReference), or it is empty. This rule fires only when validating against the XRechnung profile — plain EN 16931 and Peppol BIS treat BT-10 as optional.
How to fix it
Ask your buyer for their Leitweg-ID (B2G) or any reference they gave you (B2B), and set it:
{ "buyerReference": "04011000-12345-67" } <cbc:BuyerReference>04011000-12345-67</cbc:BuyerReference>
A Leitweg-ID looks like NNNNNNNN-XXXXX-NN (coarse routing – fine routing – check digits). If your B2B buyer gave you no reference, many suppliers repeat the order number — the field must simply be non-empty and meaningful to the buyer.
Check your invoice now. Paste it into the free validator — it flags BR-DE-15 and every other EN 16931, Peppol and XRechnung rule, each with the fix.
Or run the same check via API:
curl -X POST https://fakturwire.com/v1/validate \
-H "authorization: Bearer $FW_KEY" \
-d '{"invoice": { ... }, "profile": "xrechnung"}'