# BT-29 Seller identifier

General identifier of the seller, for example a registry number or network identifier.

> BT-29 (Seller identifier) is an additional identifier for the supplier — typically a GLN, DUNS, or scheme-qualified ID. Optional under EN 16931. Useful for buyers who route invoices on identifiers other than VAT. The scheme ID (e.g. 0088 for GLN) prefixes the value. Example: 0088:1234567890123.
>
> BT-29 · EN 16931 / XRechnung 3.x

## BT Reference Card

Canonical EN 16931 / XRechnung facts for this business term — citable from this anchor.

- **BT code**: BT-29
- **Name**: Seller identifier
- **Cardinality**: Optional (O)
- **Business group**: BG-4 SELLER
- **Data type**: Identifier
- **Example value**: 0088:1234567890123

## Quick answer

General identifier of the seller, for example a registry number or network identifier.

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

- validate
- convert

## In plain language

General identifier of the seller, for example a registry number or network identifier.

General identifier of the seller, for example a registry number or network identifier.

This identifier helps buyers and automated systems identify the supplier even when names vary.

## What you usually enter here

Structured seller identifier

Typical valid values include: 9930:DE123456789

Optional according to EN 16931-1, but one of BT-29, BT-30, or BT-31 is needed by BR-CO-26 to identify the seller automatically.

## What goes wrong often

Avoid values like: seller

Relevant rule codes: BR-CO-26

## Examples in context

This identifier helps buyers and automated systems identify the supplier even when names vary.

Optional according to EN 16931-1, but one of BT-29, BT-30, or BT-31 is needed by BR-CO-26 to identify the seller automatically.

## Valid Examples

- 9930:DE123456789

## Invalid Examples

- seller

## Related Fields

This identifier helps buyers and automated systems identify the supplier even when names vary.

- [BT-30 Seller legal registration identifier](/resources/xrechnung/bt-30-seller-legal-registration-identifier)
- [BT-31 Seller VAT Identifier](/resources/xrechnung/bt-31-seller-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-29

### Data Type:
identifier

### Cardinality:
0..1

### Requirement:
Optional

### Max Length:
50 characters

### Since Version:
Optional

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:AccountingSupplierParty/cac:Party/cac:PartyIdentification/cbc:ID
```

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

## Validation Rules

### BR-CO-26
BR-CO-26

## Why the standard cares about this field

### Business Context
This identifier helps buyers and automated systems identify the supplier even when names vary.

### Legal Requirement
Optional according to EN 16931-1, but one of BT-29, BT-30, or BT-31 is needed by BR-CO-26 to identify the seller automatically.

## 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)