# UBL-SR-26

> Payment reference shall occur maximum once

Checked against Peppol BIS Billing 3.0 2026.5

Canonical: https://einvoicecheck.eu/rules/ubl-sr-26

## Official rule text

Payment reference shall occur maximum once

## Why did my invoice fail UBL-SR-26?

The Payment reference (BT-83), in cac:PaymentMeans/cbc:PaymentID, is the remittance reference the buyer quotes when paying (e.g. a structured creditor reference), and it may occur at most once. EN 16931 models a single payment reference for the invoice.

## Common causes

- cbc:PaymentID is repeated inside a single cac:PaymentMeans element.
- Multiple cac:PaymentMeans elements each carry a different PaymentID.
- Both an OCR/KID reference and an invoice number are emitted as separate PaymentID values.

## How do I fix it?

```
Use a single reference: <cac:PaymentMeans>...<cbc:PaymentID>RF18539007547034</cbc:PaymentID>...</cac:PaymentMeans> and remove any additional PaymentID occurrences.
```