# BR-02

> The invoice is missing an Invoice number (BT-1). Every invoice must carry a unique identifier in cbc:ID.

Checked against Peppol BIS Billing 3.0 2026.5

Canonical: https://einvoicecheck.eu/rules/br-02

## Official rule text

An Invoice shall have an Invoice number (BT-1).

## Why did my invoice fail BR-02?

Every invoice must have an Invoice number (BT-1), a unique identifier assigned by the seller that distinguishes this invoice from all others they issue. It is essential for referencing, matching payments, and audit. In UBL it is the cbc:ID element directly under the Invoice root.

## Common causes

- cbc:ID at the invoice root is missing.
- The element is present but has an empty value.
- Draft or template invoices generated without an assigned number.
- A namespace error causes the ID to be read from the wrong element.

## How do I fix it?

```
<cbc:ID>INV-2026-000123</cbc:ID>
```