# Customize transactions

Source: https://developer.avalara.com/products/communications/integration-guides/communications-integration/nez4801204646957/

Guide: Communications

# Customize transactions

Learn how to customize transactions to meet your business needs and optimize system performance.

-   Pass the `client_id` and `client_profile_id` in the request header.

    -   Passing the `client_id` and `client_profile_id` fields allows for future support of multiple profiles and clients.
    -   It’s easier to include these fields early in your development effort than add the fields later when it becomes necessary.
    -   Use `0` for (the default System profile) for `client_profile_id` if you don't have a customized client profile.
-   Observe the hard limits per request:

    -   1,000 invoice lines (`inv`)
    -   10,000 line items (`itms`)
-   Use client profiles to define customizations
-   Modify transactions to meet your business needs
-   Set the [Request Config](https://developer.avalara.com/api-reference/communications/v2/models/Configuration/) (`cfg`) options to customize your response output.

    -   Use the Reporting Information Fields to connect data from the billing application to Reporting easily.
    -   Configure the amount of information returned in the response using the Return Non-Billable Taxes (`retnb`) flag and the Return Extended Data (`retext`) flag.