# BR-18 Seller tax representative name is required when the party is present

The Seller tax representative name (BT-62) shall be provided when the Seller (BG-4) has a Seller tax representative party (BG-11).

## Problem Description

The Seller tax representative name (BT-62) shall be provided when the Seller (BG-4) has a Seller tax representative party (BG-11).

> **ERROR**: XRechnung 3.0

## Context and Significance

This is a core EN16931 conditional rule; where a tax representative acts for the seller, the representative must be named for VAT accountability.

## Solution

When a cac:TaxRepresentativeParty group is present, add cac:TaxRepresentativeParty/cac:PartyName/cbc:Name with its name.

- validate
- convert

## Valid Examples

- cac:TaxRepresentativeParty present with BT-62 = VAT Rep Services Ltd

## Invalid Examples

- cac:TaxRepresentativeParty is present but has no cac:PartyName/cbc:Name

## Code Examples

### Valid XML
```
<cac:TaxRepresentativeParty>
  <cac:PartyName>
    <cbc:Name>VAT Rep Services Ltd</cbc:Name>
  </cac:PartyName>
</cac:TaxRepresentativeParty>
```

### Invalid XML
```
<cac:TaxRepresentativeParty>
  <cac:PostalAddress>
    <cac:Country>
      <cbc:IdentificationCode>DE</cbc:IdentificationCode>
    </cac:Country>
  </cac:PostalAddress>
</cac:TaxRepresentativeParty>
```

## Affected Fields

- [BT-62 Seller tax representative name](/resources/xrechnung/bt-62-seller-tax-representative-name)
- [BG-11 Seller tax representative party](/resources/xrechnung)

## Related Rules

- [BR-19](/resources/kosit-validator-errors/br-19-tax-representative-address-required)
- [BR-20](/resources/kosit-validator-errors/br-20-tax-representative-country-code-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.