Mastering Google Tag Configuration in GA4: Best Practices for Accurate Data Tracking

After auditing the GA4 setups of numerous websites across different industries, one persistent issue has become clear: the configuration of the Google Tag is often the most error-prone component. Despite companies' best efforts, misconfigurations are common, leading to inaccurate data collection and flawed decision-making. The Google Tag is the foundation of any GA4 setup, and errors here can result in significant data inconsistencies. Below are some common problems encountered when the Google Tag is misconfigured:

SNO	Issue	Description
1	Missing session_start event	An unusually low session count may occur, sometimes even lower than the number of users, which should never happen.
2	(not set) traffic sources	Missing session_start can cause misattribution and result in (not set) traffic sources or incorrect channel groupings.
3	Timing issues	Timing conflicts between the Google Tag and GA4 event tags can arise, particularly when custom parameters are set in the Google Tag.

In this article, we will explore best practices for configuring the Google Tag in GA4 to ensure reliable and actionable insights.

Before diving into best practices, it’s essential to understand the purpose of the Google Tag. It performs the following functions:

• Loads your GA4 property

• Declares configuration parameters (common settings)

• Sets GA4 cookies

• Sends automatically collected and enhanced measurement events

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Separate Pageview Event  from the Google Tag

Although the Google Tag can automatically send page_view events to GA4, it's best not to use this feature. It may interfere with the session_start event. Instead, disable the page_view in the Google Tag and send it as a separate event. This ensures that the Google Tag can load the property, send important events (like session_start), and avoid interference.

When creating a separate page_view event, include relevant custom parameters such as content_group, page_type, and page_id. 

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Fire the Google Tag on Initialization

It’s crucial to fire the Google Tag during page initialization in Google Tag Manager (GTM). This ensures it activates before any major page events occur, reducing the risk of missing key user interactions. Triggering the tag on initialization improves accuracy, ensuring that events like page views and conversions are captured from the moment the page begins to load.

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Proper Use of Configuration Parameters

Remember, the primary role of the Google Tag is to load configuration parameters, which include default GA4 parameters like page_title, page_location, and page_referrer. Use the configuration settings variable or Google Tag configuration settings to adjust these parameters. Avoid passing custom parameters in the Google Tag itself, as they may not be available during initialization. 

Instead, add custom parameters to the event settings variable or in the event settings section of a GA4 event tag. Use the event settings variable for global parameters and local settings for event-specific variables. 

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Summary

Auditing GA4 setups across various industries reveals that the most common issue lies in the misconfiguration of the Google Tag, which can result in inaccurate data and flawed decision-making. Key problems include missing session_start events, misattributed traffic sources, and timing conflicts between tags. Best practices recommend separating the page_view event from the Google Tag, firing the tag during page initialization, and properly managing configuration parameters. Custom parameters should not be set in the Google Tag but rather in event-specific settings to ensure proper tracking.