# Customer codes

Source: https://developer.avalara.com/marketplace-integration-guide/designing/customer-codes/

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

Pass your unique customer IDs in the `customerCode` field. This field is important for identifying exempt customers within AvaTax, whether through AvaTax or Exemption Certificate Management. This code represents the customer identifier from the source system being sent within the request.

**Advice**:

-   Consider hard coding a guest customer code fro customers who check out without creating an account.
-   Avoid using PII (personally identifiable information) for customer codes, such as email addresses or full names.

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

```
{  ...  "type": "SalesInvoice",  "companyCode": "DEFAULT",  "date": "2024-07-10",  "code": "XYZ",  "customerCode": "ABC",  "purchaseOrderNo": "123456789",  "commit": true,  "currencyCode": "USD",  "description": "Yarn"} 
```