Attestwire › Rule reference › BR-28

BR-28 The item gross price must not be negative

noun · EN 16931 · fatal · BT-148

For a sample invoice, the library reports: Line 1 (id "1") has a negative item gross price (BT-148: -200). The gross price is the list price *before* the item price discount (BT-147) is taken off, so it is the larger of the two figures by construction — a negative one means the sign has been applied at the wrong end.

Business term

BT-148

Severity

fatal

The fix

Set line.grossUnitPrice to the positive list price and line.priceDiscount to the reduction. If the price genuinely is the net price, omit grossUnitPrice entirely — this build derives the discount as grossUnitPrice − unitPrice when you do not state it.

A passing value

"grossUnitPrice": 200, "priceDiscount": 50, "unitPrice": 150

What the library returns

The full error returned by @attestwire/en16931. It includes the rule ID, affected field and suggested correction. Developers can use this object in their application:

{
  "rule": "BR-28",
  "field": "BT-148",
  "severity": "fatal",
  "message": "Line 1 (id \"1\") has a negative item gross price (BT-148: -200). The gross price is the list price *before* the item price discount (BT-147) is taken off, so it is the larger of the two figures by construction — a negative one means the sign has been applied at the wrong end. EN 16931 models every reduction as an allowance or a discount, never as a negative price, and BR-27 says the same thing about the net price (BT-146).",
  "fix": "Set line.grossUnitPrice to the positive list price and line.priceDiscount to the reduction. If the price genuinely is the net price, omit grossUnitPrice entirely — this build derives the discount as grossUnitPrice − unitPrice when you do not state it.",
  "example": "\"grossUnitPrice\": 200, \"priceDiscount\": 50, \"unitPrice\": 150",
  "xpath": "/ubl:Invoice/cac:InvoiceLine[1]/cac:Price/cac:AllowanceCharge/cbc:BaseAmount",
  "docsUrl": "https://attestwire.com/rules/BR-28"
}

xpath is always a UBL path. On a CII invoice, look for the matching CII field instead.