# BR-28

Quoted from a public specification. This page is not a validator, and it is not tax, legal, or accounting advice.

- Country: EU
- Syntax: UBL
- Severity: fatal
- Statement language: en
- Last verified: 2026-10-18

## Official statement

> The Item gross price (BT-148) shall NOT be negative.

Source: https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/BR-28/

Peppol BIS Billing 3.0, May 2026 release, EN 16931 model bound to UBL

Severity note: fatal, from the Flag column of the Peppol BIS Billing 3.0 UBL rules index retrieved 2026-10-18.

## Plain-language reading

The item gross price (BT-148) must not be negative. The official message capitalizes NOT. The published test checks that the gross price base amount is greater than or equal to zero, or that the base amount is absent. The absent branch calls exists. The comparison has spaces around >=. The context is the invoice line or the credit note line.

## What to change

Set the item gross price (BT-148) to zero or a positive amount, or leave the gross price base amount out.

## Illustration

Illustration of the condition in the official statement. Not an example published by the source.

**Fails the stated condition.** The gross price base amount is present and less than zero.

**Passes the stated condition.** The gross price base amount is zero or greater, or the line has no gross price base amount.

## Published context and test

Copied from the source. Not reimplemented on this page.

```
cac:InvoiceLine | cac:CreditNoteLine
```

```
(cac:Price/cac:AllowanceCharge/cbc:BaseAmount) >= 0 or not(exists(cac:Price/cac:AllowanceCharge/cbc:BaseAmount))
```

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