# UBL-SR-23

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

> Seller tax representative VAT identifier shall occur maximum once, if the Seller has a tax representative

Source: https://docs.peppol.eu/poacc/billing/3.0/rules/ubl-tc434/UBL-SR-23/

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 seller tax representative VAT identifier shall occur at most once if the seller has a tax representative. The statement has a comma and no period. It says shall, says identifier, and capitalizes Seller and VAT. The flag is fatal. The context is cac:TaxRepresentativeParty. The published test counts party tax-scheme company identifiers. It does not compare the tax scheme to VAT. The count comparison has a space before <= and a space after it.

## What to change

Send at most one tax representative tax-scheme company identifier.

## Illustration

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

**Fails the stated condition.** The tax representative party has two tax-scheme company identifiers.

**Passes the stated condition.** The tax representative party has one tax-scheme company identifier, or none.

## Published context and test

Copied from the source. Not reimplemented on this page.

```
cac:TaxRepresentativeParty
```

```
(count(cac:PartyTaxScheme/cbc:CompanyID) <= 1)
```

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