# Entity use code (header and line levels)

Source: https://developer.avalara.com/ecommerce-integration-guide/transactions/certification-requirements/entity-use-code/

**Element type:** Suggested

**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/)

If your application allows for inputting exempt reasons for exempt customers, then your integration should also include this functionality. This can be done using the `entityUseCode` field at either the document or line level. Refer to the [Entity use codes](/ecommerce-integration-guide/designing/entity-use-codes) topic earlier in this guide for more information.

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

```
 {  "lines": [      {    "number": "1",    "quantity": 1,    "amount": 100,    "taxCode": "PC002386",    "itemCode": "CARPET",    "description": "Bulk carpeting"      },      {    "number": "2",    "quantity": 6,    "amount": 75,    "taxCode": "PT118906",    "itemCode": "TOOLS",    "description": "Carpet installation tools",    "entityUseCode": "TAXABLE"      }  ],  ...}
```