# 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

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

- [Validate XML](/en/xrechnung-validator?source=resource&bt=BT-63)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&bt=BT-63)

## In plain language

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.

## Where the field sits

BT-63 belongs to the Seller part of the invoice. UBL 2.1 Syntax: Invoice › cac:TaxRepresentativeParty › cac:PartyTaxScheme[cac:TaxScheme/upper-case(cbc:ID)="VAT"] › cbc:CompanyID. CII (UN/CEFACT) Syntax: rsm:CrossIndustryInvoice › rsm:SupplyChainTradeTransaction › ram:ApplicableHeaderTradeAgreement › ram:SellerTaxRepresentativeTradeParty › ram:SpecifiedTaxRegistration › ram:ID[@schemeID="VA"].

## What goes wrong often

Avoid values like: 123456789, DE 123456789

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

## Valid Examples

- DE123456789
- FRAB123456789

## Invalid Examples

- 123456789
- DE 123456789

## Related Fields

- [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

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:TaxRepresentativeParty/cac:PartyTaxScheme[cac:TaxScheme/upper-case(cbc:ID)="VAT"]/cbc:CompanyID
```

### CII (UN/CEFACT) Syntax
```
/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ram:SellerTaxRepresentativeTradeParty/ram:SpecifiedTaxRegistration/ram:ID[@schemeID="VA"]
```

## Validation Rules

### BR-56
BR-56

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

## Check whether your XRechnung sets BT-63 correctly

Upload the XML file to the free validator. It applies the KoSIT rules for XRechnung 3.0 and names each finding with its rule ID, for this field for example BR-56, BR-CO-09. Creating a new invoice instead? The converter checks the invoice against the same rules and shows the findings before download.

- [Validate XML](/en/xrechnung-validator)
- [Convert invoice](/en/pdf-to-xrechnung)

Free, no account needed. XML file up to 2 MB.

## Official sources and tools

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