Validation rules

BR-CO-04

An invoice line is not categorized with a VAT category code (BT-151).

Rule: BR-CO-04 — official EN 16931 / XRechnung rule
Severity: error
Business term: BT-151 — Line VAT category
Field in your JSON: invoice.lines[*].vat_category
Detected by: tier 3 — KoSIT validator (authoritative)
Reachability: Only reachable when validating your own XML — normbill-generated documents cannot trigger it

The engine derives a category for every line it serializes; a line with neither vat nor vat_category is stopped at tier 1 (NB-VAT-RATE) before generation.

How to fix it

Add cac:ClassifiedTaxCategory with a UNCL 5305 code (S, Z, E, AE, K, G, O, L, M) to the line's cac:Item.

BR-CO-04 auf Deutsch — was bedeutet der Fehler?

Eine Rechnungsposition ist keiner Umsatzsteuer-Kategorie (BT-151) zugeordnet.

So beheben Sie den Fehler

Ergänzen Sie cac:ClassifiedTaxCategory mit einem UNCL-5305-Code (S, Z, E, AE, K, G, O, L, M) im cac:Item der Position.

Official sources

Every 422 from the API lists the rule id, the path in your request JSON, a plain-language message and a suggested fix — see the docs overview for the report format.

Or try it live: drop any XRechnung XML on the free validator — same KoSIT-backed report, no account.