Cross Domain Tracking in Google Analytics 4: Addressing A Common Misunderstanding

So, subdomains are covered when users navigate across them; it’s often a misconception that cross domain tracking needs to be turned on in Google Analytics for subdomains.

For actual, distinct domains, GA4 has made it simpler than GA3. That is when you’d turn on cross domain tracking to not “double count” a session since it’s a self-referral. These are the cases when you need to turn on cross domain tracking to solve for this.

To do this, both domains must have the same GA property on them. Then, you simply add both domains under the?Datastream > Configure Tag Settings > Configure Domains section?in the GA interface. GA will pass a parameter in the URL when a visitor goes from the first domain to the second, which you can verify by checking the URL.