# Business identification number

Source: https://developer.avalara.com/vat-ecom/transactions/certification-requirements/business-identification-number/

**Element type:** Required

**Endpoints/models used:** [CreateTransactionModel](https://developer.avalara.com/api-reference/avatax/rest/v2/models/CreateTransactionModel/), [LineItemModel](https://developer.avalara.com/api-reference/avatax/rest/v2/models/LineItemModel/)

For EU transactions, the `businessIdentificationNo` is a separate identifier that relates to the counterparty's VAT Registration number in a transaction. You can specify this at either the document level or the line level. When specified at the document level, this value applies to all lines in the transaction.

If you specify a VAT business identification number for the customer in a transaction and you also set up a business identification number for your company during company setup, the transaction will be treated as a B2B transaction for VAT purposes, and it will be calculated according to VAT tax rules.

Consider the following when using this field:

-   When the document type is `SalesOrder` or `SalesInvoice`, this is the final customer's VAT number. It’s only relevant for B2B transactions. When populated, it must include the VAT country two-digit ISO code prefix (for example `"DE123456789"`).

-   Users can omit this field for B2C transactions.

-   When the document type is `PurchaseOrder` or `PurchaseInvoice`, this represents the vendor’s VAT number.

[![Closed](https://avalara-devdocs-prod.mcoutput.com/vat-ecom/Skins/Default/Stylesheets/Images/transparent.gif)View example](javascript:void\(0\);)

```
 {  "type": "PurchaseInvoice",  "date": "2024-07-24",  "companyCode": "CRUSH",  "customerCode": "userMP",  "code": "userMP",  "isSellerImporterOfRecord": false,  "businessIdentificationNo": "ATU12233456",  "debugLevel": "Diagnostic",  "detailLevel": "Diagnostic",  ...}
```