Mandatory tags are automatically assigned to a task on the timesheet when the timing for that task begins and they cannot be removed by users.
Mandatory tags are available only in the Ultimate plan.
To enable this option, navigate to the Projects tab on the left side menu. Next, click on the project or task to open its edit panel and assign tags. After assigning the tag, check the Mandatory box next to the tag’s name.
That’s it - now each time you will start tracking time to a task with a mandatory tag it will be assigned to the time entry automatically.
If you set the entire list of tags as mandatory users will need to manually select a tag from this list when running the timer. The "Start timer" button will be blocked until a tag from the mandatory list is assigned.