Guide
Leitweg-ID for developers
BT-10 is the most common rejection when sending XRechnung to German public buyers. What the id is, which format applies, and where it goes in your JSON.
What it is
The Leitweg-ID routes the invoice to the right public-sector recipient in Germany. In EN 16931 the field is Buyer reference (BT-10). XRechnung makes it mandatory for public procurement — rule BR-DE-15.
Format
Typical pattern: {coarse}-{fine}-{check}, e.g. 04011000-1234512345-06.
- Coarse addressing: 2–12 digits
- Fine addressing (optional): 1–30 alphanumeric
- Check digits: exactly 2 digits
Format OK — this is what normbill expects in invoice.buyer_reference (tier-1).
Note: Official KoSIT Schematron for BR-DE-15 only checks presence — not syntax. Format checking is normbill tier-1 (NB-LEITWEG-FORMAT).
In the normbill request
{
"format": "xrechnung-3.0",
"invoice": {
"buyer_reference": "04011000-1234512345-06",
...
}
}If the field is missing, generate returns 422 with path: "invoice.buyer_reference" and a concrete fix — not only the raw Schematron text.
KoSIT vs tier-1
- BR-DE-15 (KoSIT): field must be present
- NB-LEITWEG-FORMAT (normbill): format as above — so you catch syntax issues before the sidecar
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