Validation rules

BR-27 — EN 16931 rule

The item net price (BT-146) must not be negative.

Rule: BR-27 — official EN 16931 / XRechnung rule
Severity: error
Business term: BT-146 — Item net price
Field in your JSON: invoice.lines[*].unit_price

How to fix it

Use a positive unit_price — a cancellation or correction (type_code 384) reverses lines with a negative qty instead.

Cancellation, correction or credit note — which type code applies, and why a UBL Invoice rejects 381: see the guide on cancellations, corrections and credit notes.

BR-27 auf Deutsch — was bedeutet der Fehler?

Der Netto-Einzelpreis einer Position (BT-146) darf nicht negativ sein.

So beheben Sie den Fehler

Verwenden Sie einen positiven unit_price. Stornos und Rechnungskorrekturen (type_code 384) kehren Positionen über eine negative Menge (qty) um — nie über einen negativen Preis.

Welcher Typcode für Storno, Korrektur oder Gutschrift gilt: Leitfaden zu Storno, Korrektur und Gutschrift.

Related rules

PEPPOL-EN16931-R046 — The item net price must equal the gross price minus the price allowance when a gross price is provided.
BR-26 — An invoice line has no item net price (BT-146).
BR-28 — The item gross price (BT-148) must not be negative.
BR-29 — The invoicing period end date (BT-74) must not be earlier than its start date (BT-73).
BR-25 — An invoice line has no item name (BT-153).
BR-30 — An invoice line period end date (BT-135) must not be earlier than its start date (BT-134).

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.