Auth0 Support Center - How to override sub in ID token to contain a custom field instead of user

How to override sub in ID token to contain a custom field instead of user_id

Sep 10, 2025

Overview

There are multiple threads in Auth0 community indicating that it is not possible to change the default mapping of user's user_id field to sub in the ID Token.
Need to confirm whether this restriction still applies to the latest release of Auth0 private instance?

Solution

I'm afraid this is still not possible, I would suggest leaving some feedback directly to our Product Team about this to suggest the sub field to be customizable, please use our Feedback forum found at https://auth0.com/feedback to submit your request.

You could however add required custom claim to id token using actions, please see the link below:
https://auth0.com/docs/get-started/apis/scopes/sample-use-cases-scopes-and-claims#add-custom-claims-to-a-token