# BT-63 Seller tax representative VAT identifier

VAT identifier of the seller tax representative. Enter the VAT number with the country prefix used by the representative.

## Quick answer

VAT identifier of the seller tax representative. Enter the VAT number with the country prefix used by the representative.

> **Seller details**: Who issued the invoice and how the recipient can identify that business reliably.

- validate
- convert

## In plain language

VAT identifier of the seller tax representative. Enter the VAT number with the country prefix used by the representative.

VAT identifier of the seller tax representative. Enter the VAT number with the country prefix used by the representative.

Validators use this identifier in VAT scenarios where the fiscal representative stands in for the seller toward the tax administration.

## What you usually enter here

Country code prefix plus VAT number

Typical valid values include: DE123456789, FRAB123456789

Required by BR-56 for each seller tax representative party. It must carry an ISO 3166-1 alpha-2 country prefix according to BR-CO-09.

## What goes wrong often

Avoid values like: 123456789, DE 123456789

Relevant rule codes: BR-56, BR-CO-09

## Examples in context

Validators use this identifier in VAT scenarios where the fiscal representative stands in for the seller toward the tax administration.

Required by BR-56 for each seller tax representative party. It must carry an ISO 3166-1 alpha-2 country prefix according to BR-CO-09.

## Valid Examples

- DE123456789
- FRAB123456789

## Invalid Examples

- 123456789
- DE 123456789

## Related Fields

Validators use this identifier in VAT scenarios where the fiscal representative stands in for the seller toward the tax administration.

- [BT-62 Seller tax representative name](/resources/xrechnung/bt-62-seller-tax-representative-name)
- [BT-31 Seller VAT Identifier](/resources/xrechnung/bt-31-seller-vat-identifier)
- [BT-32 Seller tax registration identifier](/resources/xrechnung/bt-32-seller-tax-registration-identifier)

## XML mapping and field facts

Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details.

### Field ID:
BT-63

### Data Type:
identifier

### Cardinality:
1..1

### Requirement:
Mandatory

### Max Length:
30 characters

### Since Version:
Conditional

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:TaxRepresentativeParty/cac:PartyTaxScheme/cbc:CompanyID
```

### CII (UN/CEFACT) Syntax
```
/CrossIndustryInvoice/SupplyChainTradeTransaction/ApplicableHeaderTradeAgreement/ram:SellerTaxRepresentativeTradeParty/ram:SpecifiedTaxRegistration/ram:ID
```

## Validation Rules

### BR-56
BR-56

### BR-CO-09
BR-CO-09

## Why the standard cares about this field

### Business Context
Validators use this identifier in VAT scenarios where the fiscal representative stands in for the seller toward the tax administration.

### Legal Requirement
Required by BR-56 for each seller tax representative party. It must carry an ISO 3166-1 alpha-2 country prefix according to BR-CO-09.

## Official sources and tools

- [KoSIT Validator](https://erechnungsvalidator.service-bw.de/)
- [Invoice Converter](/pdf-to-xrechnung)
- [XRechnung Standard](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)