# Middleman VAT ID

Source: https://developer.avalara.com/vat-erp/certification-requirements/middleman-vat-id/

**Element type:** Required for Triangulation

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

Your integration must allow users to specify the VAT id of the middleman in triangulation scenarios. This is done using the `MiddlemanVatId` parameter in the [TransactionParameterModel](https://developer.avalara.com/api-reference/avatax/rest/v2/models/TransactionParameterModel/) or [TransactionLineParam](https://developer.avalara.com/api-reference/avatax/rest/v2/models/TransactionLineParameterModel/)[eterModel](https://developer.avalara.com/api-reference/avatax/rest/v2/models/TransactionLineParameterModel/). When providing the `MiddlemanVatId`, you must include the complete VAT ID, starting with the two-digit country ISO prefix.

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

```
 {  "parameters":[    {      "name": "Transport",      "value": "Seller"    },    {      "name": "IsTriangulation",      "value": "true"    },    {      "name": "MiddlemanVatId",      "value": "DK12345678"    }  ]  ...}
```