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How to set up GA4 cross-domain tracking

Live guide · Checked 28 October 2026 · Updated 28 October 2026 · Checked every week against Google Analytics 4's own help pages

Keep one visit as one visitor when people move between your site and your booking, shop or checkout domain, so leads and sales are credited to the right source.

Time
15 minutes
You will need
  • The same GA4 measurement ID on every domain
  • Edit access to the GA4 property
Stuck?
Troubleshooting or ask us a question

Step by step

  1. List your domains

    Write down every domain people move between, for example example.com, shop.example-store.com and book.example-bookings.com. Subdomains of the same site (www. and shop. of one domain) don't need this: GA4 already treats them as one.

  2. Use one measurement ID everywhere

    Each domain must send to the same GA4 property with the same measurement ID (G-...), usually through the same Google tag.

  3. Configure your domains

    In GA4 go to Admin > Data streams, open your web stream, then Configure tag settings > Configure your domains. Add each domain with Match type Contains and save:

    Text
    example.com
example-store.com
example-bookings.com

  4. Stop self-referrals

    On the same Configure tag settings page open Show more > List unwanted referrals and add your payment and booking providers (for example pay.example-payments.com), so returns from them don't start a new visit.

  5. Test the link

    Click a link from one domain to another. The address on the second domain should carry a _gl= part, like this:

    Text
    https://shop.example-store.com/?_gl=1*abc123*_ga*MTIzNDU2*_ga_AB12CD34EF*MTY5...

    If it's there, the visit carries across.

  6. Check it in GA4

    In DebugView, the same device should show one stream of events across both domains. After a few days, Reports > Acquisition > Traffic acquisition should show fewer visits from your own domains as referrals.

Tips from people who set these up every week

  • Links added by JavaScript after the page loads are decorated too, but forms that post to another domain may not be: test your booking and checkout buttons.
  • If a domain uses a different Tag Manager container, check it uses the same measurement ID.

Troubleshooting: questions and answers

The _gl part is missing.

The link may open in a new window through JavaScript, or the domain isn't in Configure your domains. Check the spelling and that Match type is Contains.

My own domain still shows as a referral.

Add it to List unwanted referrals, and check every page on that domain has the Google tag.

Official help pages

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