Validation rules

BR-B-01 — EN 16931 rule

VAT category "B" (Italian split payment) is only allowed on domestic Italian invoices — every country code in the document must be IT.

Rule: BR-B-01 — 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 request schema's VAT category enum has no code "B", so only XML submitted to /v1/invoices/validate can carry it.

How to fix it

Use category "S" (or the applicable category) unless both parties are in Italy.

BR-B-01 auf Deutsch — was bedeutet der Fehler?

Die Kategorie "B" (italienisches Split Payment) ist nur auf rein italienischen Rechnungen zulässig — jeder Ländercode im Dokument muss IT sein. normbill akzeptiert die Kategorie B gar nicht; die Meldung betrifft extern erzeugtes XML.

So beheben Sie den Fehler

Verwenden Sie die Kategorie "S" (bzw. die zutreffende Kategorie), sofern nicht beide Parteien in Italien sitzen.

Related rules

BR-O-11 — VAT category "O" (not subject to VAT) cannot be mixed with other VAT categories on the same invoice…
BR-CO-04 — An invoice line is not categorized with a VAT category code (BT-151).
BR-AE-01 — Lines or document-level allowances/charges use VAT category "AE" (reverse charge), so the VAT breakdown…
BR-B-02 — VAT category "B" (Italian split payment) must not be combined with category "S" (standard rated) on the same…
BR-E-01 — Lines or document-level allowances/charges use VAT category "E" (exempt), so the VAT breakdown (BG-23) must…
BR-G-01 — Lines or document-level allowances/charges use VAT category "G" (export outside the EU), so the VAT…

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.