# Client profile ID

Source: https://developer.avalara.com/products/communications/integration-guides/communications-integration/cjw7412028792908/

Guide: Communications

# Client profile ID

**Element type: Required**

**Endpoints/models used: N/A**

Your integration must include an option to specify a client profile ID in the header. If a user doesn’t specify a client profile ID, then the system should use the RESTv2 system default profile.

Client profiles you to customize how the AFC tax engine interprets a request and returns tax results. These customizations can include:

-   Bundles
-   Exclusions
-   Tax Override
-   AFC Tax Engine configuration

**Why use a client profile?**

Reasons to use a client profile can include:

-   Profiles are cached; this speeds up response times.
-   Using a client profile eliminates including the same customization, such as a tax override, in each CalcTaxes request.
-   Multiple profiles can be applied to your client ID. Example uses for multiple profiles include:
    -   Separate configurations for different types of transactions
    -   Separate configurations for child companies
    -   Testing new configurations

**How to apply a client profile to a session**

When authenticating to Communications REST v2, pass the client profile ID in the header using `client_profile_id`.