# BT-32 Seller tax registration identifier

Tax registration identifier of the seller used in domestic tax processes.

## Quick answer

Tax registration identifier of the seller used in domestic tax processes.

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

## In plain language

Tax registration identifier of the seller used in domestic tax processes.

Tax registration identifier of the seller used in domestic tax processes.

This field complements the VAT ID when the tax administration or the buyer expects the domestic tax number as well.

## What you usually enter here

Domestic tax registration number

Typical valid values include: 123/4567/8901

Optional according to EN 16931-1.

## What goes wrong often

Avoid values like:

## Examples in context

This field complements the VAT ID when the tax administration or the buyer expects the domestic tax number as well.

Optional according to EN 16931-1.

## Valid Examples

- 123/4567/8901

## Related Fields

This field complements the VAT ID when the tax administration or the buyer expects the domestic tax number as well.

- [BT-31 Seller VAT Identifier](/resources/xrechnung/bt-31-seller-vat-identifier)
- [BT-63 Seller tax representative VAT identifier](/resources/xrechnung/bt-63-seller-tax-representative-vat-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-32

### Data Type:
identifier

### Cardinality:
0..1

### Requirement:
Optional

### Max Length:
30 characters

### Since Version:
Optional

## XML Implementation

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

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

## Why the standard cares about this field

### Business Context
This field complements the VAT ID when the tax administration or the buyer expects the domestic tax number as well.

### Legal Requirement
Optional according to EN 16931-1.

## 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)