# BR-56 Seller tax representative must have a VAT identifier

Each Seller tax representative party (BG-11) shall have a Seller tax representative VAT identifier (BT-63).

## Problem Description

Each Seller tax representative party (BG-11) shall have a Seller tax representative VAT identifier (BT-63).

> **ERROR**: XRechnung 3.0

## Context and Significance

This rule comes from the EN16931 core semantic model enforced by the KoSIT XRechnung 3.0.2 Schematron, ensuring invoices carry the mandatory data needed for automated processing.

## Solution

Add cac:TaxRepresentativeParty/cac:PartyTaxScheme/cbc:CompanyID with the representative’s VAT identifier under a VAT tax scheme.

- validate
- convert

## Valid Examples

- BT-63 = FR12345678901 for the tax representative

## Invalid Examples

- Tax representative party with name and address but no BT-63 VAT ID

## Code Examples

### Valid XML
```
<cac:TaxRepresentativeParty>
  <cac:PartyTaxScheme>
    <cbc:CompanyID>FR12345678901</cbc:CompanyID>
    <cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme>
  </cac:PartyTaxScheme>
</cac:TaxRepresentativeParty>
```

### Invalid XML
```
<cac:TaxRepresentativeParty>
  <cac:PartyName><cbc:Name>Fiscal Rep GmbH</cbc:Name></cac:PartyName>
</cac:TaxRepresentativeParty>
```

## Affected Fields

- [BT-63 Seller tax representative VAT identifier](/resources/xrechnung/bt-63-seller-tax-representative-vat-identifier)

## Related Rules

- [BR-56](/resources/kosit-validator-errors/br-56-tax-representative-vat-identifier-required)

## Validation Tools

- [Official KoSIT Validator](https://erechnungsvalidator.service-bw.de/): Validate your XRechnung files against all BR-DE rules.
- [Convert PDF to XRechnung](/pdf-to-xrechnung): Automatic validation error fixes when converting.

## Related Resources

- [Official Specification](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)
- [Complete Error List](/resources/kosit-validator-errors): Overview of all German XRechnung validation rules.