# UBL-SR-03

> Despatch advice identifier shall occur maximum once

Checked against Peppol BIS Billing 3.0 2026.5

Canonical: https://einvoicecheck.eu/rules/ubl-sr-03

## Official rule text

Despatch advice identifier shall occur maximum once

## Why did my invoice fail UBL-SR-03?

The Despatch advice reference (BT-16), which links the invoice to a preceding despatch advice document, may appear at most once on an invoice. In UBL this maps to cac:DespatchDocumentReference, and having more than one such reference at document level is not allowed under EN 16931.

## Common causes

- Mapping logic emits one cac:DespatchDocumentReference per shipment or per line-related despatch, duplicating it at header level.
- A source ERP with multiple despatch numbers concatenates them into repeated elements instead of a single value.
- Template accidentally includes the despatch reference block twice.

## How do I fix it?

```
Keep a single header-level reference: <cac:DespatchDocumentReference><cbc:ID>DESP-2026-001</cbc:ID></cac:DespatchDocumentReference> and remove any additional cac:DespatchDocumentReference elements.
```