# UBL-SR-37

> Item price discount shall occur maximum once

Checked against Peppol BIS Billing 3.0 2026.5

Canonical: https://einvoicecheck.eu/rules/ubl-sr-37

## Official rule text

Item price discount shall occur maximum once

## Why did my invoice fail UBL-SR-37?

The item price on an invoice line may show one Item price discount (BT-147), the amount deducted from the gross price to reach the net price actually charged. EN 16931 allows at most one price allowance per line, so within cac:Price the cac:AllowanceCharge (which must be an allowance, cbc:ChargeIndicator = false) may occur only once.

## Common causes

- Two cac:AllowanceCharge blocks under cac:Price on the same line.
- A charge (cbc:ChargeIndicator = true) mistakenly added under cac:Price, which is not permitted.
- Multiple stacked price discounts modelled separately instead of being netted into one.

## How do I fix it?

```
Keep one price allowance: <cac:Price>...<cac:AllowanceCharge><cbc:ChargeIndicator>false</cbc:ChargeIndicator><cbc:Amount currencyID="EUR">2.00</cbc:Amount><cbc:BaseAmount currencyID="EUR">12.00</cbc:BaseAmount></cac:AllowanceCharge></cac:Price>.
```