# UBL-SR-07

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

> If there is a preceding invoice reference, the preceding invoice number shall be present

Source: https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/UBL-SR-07/

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

If a preceding invoice reference is present, the preceding invoice number shall be present. The statement has no period and says shall. The flag is fatal. The context is cac:BillingReference, not the invoice root. The published test is (cac:InvoiceDocumentReference/cbc:ID). It does not call count and it does not use <=.

## What to change

Give each invoice document reference inside a billing reference an identifier.

## Illustration

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

**Fails the stated condition.** A billing reference has an invoice document reference and that reference has no identifier.

**Passes the stated condition.** Each invoice document reference inside a billing reference has an identifier.

## Published context and test

Copied from the source. Not reimplemented on this page.

```
cac:BillingReference
```

```
(cac:InvoiceDocumentReference/cbc:ID)
```

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