# BT-46 Buyer identifier

General identifier of the buyer, for example a customer ID, network ID, or routing ID.

> BT-46 (Buyer identifier) is an additional identifier for the buyer — GLN, DUNS, or another scheme-qualified ID. Optional under EN 16931 but used by buyers whose ERP keys are not their VAT number. The scheme ID (e.g. 0088 for GLN) qualifies the value. Example: 0088:9876543210123.
>
> BT-46 · EN 16931 / XRechnung 3.x

## BT Reference Card

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

- **BT code**: BT-46
- **Name**: Buyer identifier
- **Cardinality**: Optional (O)
- **Business group**: BG-7 BUYER
- **Data type**: Identifier
- **Example value**: 0088:9876543210123

## Quick answer

General identifier of the buyer, for example a customer ID, network ID, or routing ID.

> **Buyer details**: Who receives the invoice and which buyer records or routing data must match.

## In plain language

General identifier of the buyer, for example a customer ID, network ID, or routing ID.

General identifier of the buyer, for example a customer ID, network ID, or routing ID.

This allows suppliers and receiving systems to identify the buyer by a stable machine-readable key.

## What you usually enter here

Structured buyer identifier

Typical valid values include: CUST-10045

Optional according to EN 16931-1.

## What goes wrong often

Avoid values like:

## Examples in context

This allows suppliers and receiving systems to identify the buyer by a stable machine-readable key.

Optional according to EN 16931-1.

## Valid Examples

- CUST-10045

## Related Fields

This allows suppliers and receiving systems to identify the buyer by a stable machine-readable key.

- [BT-47 Buyer legal registration identifier](/resources/xrechnung/bt-47-buyer-legal-registration-identifier)
- [BT-49 Buyer Electronic Address](/resources/xrechnung/bt-49-buyer-electronic-address)

## 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-46

### Data Type:
identifier

### Cardinality:
0..1

### Requirement:
Optional

### Max Length:
50 characters

### Since Version:
Optional

## XML Implementation

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

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

## Why the standard cares about this field

### Business Context
This allows suppliers and receiving systems to identify the buyer by a stable machine-readable key.

### 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)