# UBL-SR-53

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

> CompanyID (VAT Identifier) must be stated when providing the PartyTaxScheme/TaxScheme/ID.

Source: https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/UBL-SR-53/

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

The company identifier must be stated when a party tax scheme identifier is present. The statement ends with a period and says must. It does not say shall. It is 89 characters. The flag is fatal. The context is a party tax scheme. The published test calls exists for the tax scheme identifier and for the company identifier. It does not call count and it does not use <=.

## What to change

Send the company identifier when the tax scheme identifier is present.

## Illustration

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

**Fails the stated condition.** A party tax scheme names a tax scheme identifier and omits the company identifier.

**Passes the stated condition.** A party tax scheme names both a tax scheme identifier and a company identifier.

## Published context and test

Copied from the source. Not reimplemented on this page.

```
cac:PartyTaxScheme
```

```
exists(cac:TaxScheme/cbc:ID) and exists(cbc:CompanyID)
```

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