Can't identify the real source of a goal because subdomains in GA

[estebanseo]

Hello,

I have one domain for my website (www.domain.com) where I receive all the new traffic and a subdomain (billing.domain.com) for the billing system.

Im tracking both in Analytics.

I have a goal (new order) configured in the subdomain -billing system-.

But when I want to track the source / medium of the goals (new orders) in billing.domain.com, always appears my main website (www.domain.com) as the referral.

Now I added in Analytics: Admin > Property > Referral Exclusion List, the www.domain.com and domain.com.

Do you think that now I can track the real referrer of the goals?

Or should I do a more complex tracking setup with Tag Manager ( https://support.google.com/tagmanager/answer/6106951 ) to pass the session cookies from a subdomain to another one, just to identify the real source / medium of the visitor?

Thank you

[Hutch42]

Have you tried treating your sub-domains like a cross domain and passing the cookie to it:

https://developers.google.com/analytics/devguides/collection/analyticsjs/cross-domain

This should fix your problem, but you will need to make sure that your URIs are unique across both your main and sub domain.