# 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: 0088:1234567890128.
>
> BT-29 · EN 16931 / XRechnung 3.x

## BT Reference Card

Key EN 16931 and XRechnung facts for this business term.

- **BT code**: BT-29
- **Name**: Seller identifier
- **Cardinality**: Optional (O)
- **Business group**: BG-4 SELLER
- **Data type**: Identifier
- **Example value**: 0088:1234567890128

## Seller details

Who issued the invoice and how the recipient can identify that business reliably.

- [Validate XML](/en/xrechnung-validator?source=resource&bt=BT-29)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&bt=BT-29)

## In plain language

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.

## Where the field sits

BT-29 belongs to the Seller part of the invoice. UBL 2.1 Syntax: Invoice › cac:AccountingSupplierParty › cac:Party › cac:PartyIdentification › cbc:ID. CII (UN/CEFACT) Syntax: rsm:CrossIndustryInvoice › rsm:SupplyChainTradeTransaction › ram:ApplicableHeaderTradeAgreement › ram:SellerTradeParty › ram:ID.

## What goes wrong often

Avoid values like: seller

Relevant rule codes: BR-CO-26

## Valid Examples

- 9930:DE123456789

## Invalid Examples

- seller

## Related Fields

- [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

## XML Implementation

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

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

## Validation Rules

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

## Check whether your XRechnung sets BT-29 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-CO-26. 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)