BT-10 — Buyer reference (route ID)

BT-10 is a reference assigned by the buyer. In the German public sector, this is the route ID that uniquely assigns an invoice to an order or budget item.

In UBL it is in cbc:BuyerReference, in CII in ram:BuyerReference. For Peppol invoices, rule R003 requires either BT-10 or a purchase order reference (BT-13).

If it is missing, the invoice will not be assigned during automatic processing and will be rejected - even if it formally complies with EN 16931.