Already billed time entries cannot be set to unbillable -> Badrequest Depending on the time entry, the calling users has to have several permissions to edit the time entries. No permissions are required if the calling user is owner of this time entry. If the calling user is not the creator of the time entry and the time entry is connected to a project, ‘write’ permissions on the ‘project-timetracking’ feature are necessary. If the time entry is connected to a task, the user needs to be assignee of this task or the user needs write permissions on: ‘project-timetracking’ if it is a project task.