Tax allows you to set a client as Private so only you or assigned users can access their details.
Private Clients
Log in to Tax.
Click on a client name to open the Edit Client Details window.
At the bottom, tick the Private Client box.
If multiple users require access to this client, click on the group icon below the tick box (it appears only after it is ticked).
Enter the User's name in the Share Private Client window and click on the username to add users.
If you need to remove existing users from this list, click on the (X) cross beside the username.
Once the list is made, click Save to close the client details window.