Linking Sign Ups

This is an advanced feature and is not enabled by default. Please contact if you would like to activate sign up linking on your project. 

In most cases it is possible to link analytics data to users by passing user details either beside a transaction ID or shared user ID. In some cases however neither of these options may be available but a link can be established with newsletter or other form sign up.

To establish this link we need to pass a unique sign up ID (which can be randomly generated) to both Google Analytics and the Thirty-One Circles tracking script, alongside the standard user information.  

To Establish the Link:

In Google Analytics:

  • Pass the unique sign up ID to a "signup_confirmation" custom event.
    • The key should be "id"
    • The value should be a string containing the unique sign up ID. 

On the website tracking scripts (API):

  • Pass the unique sign up ID to an "suid" parameter
    • This can be appended to the "Direct Permission Update" template. 

For GDPR Compliance:

When linking users using a sign up ID special care should be taken to ensure they can update their advertising consent as time goes on. 

If the sign up does not create an account to provide a way to update consent we recommend either:

  • Using a second form, (normally found via a link in the privacy policy or cookie policy) where users can submit their email to remove consent.
  • Having a manual or automatic process to update consent with changes in their CRM consent status. 

To opt out users via the API use the standard "Direct Permission Update" template and into the "c2" parameter pass "0". Like the other Thirty-One Circles API calls this can be triggered on form completion in GTM or via a server call.  


This is an advanced feature and is not enabled by default. To use sign up linking please contact

More questions?

Contact our support team at who are always ready to offer advice and assistance.