Timeslips can be 'posted', meaning they are no longer editable by any user. Posted timeslips can be viewed, but display a message explaining that they cannot be edited.

A user's role needs the "Manage Time" permission to post timeslips using the "Non-Posted Time" link on the Admin page. This permission does not override the locked state of posted timeslips; no user, including site administrators, can edit a posted timeslip.

Legacy static timeslips are automatically locked when posted.

Sites using dynamic timeslip forms must include the Display Locked/Posted Message block on each dynamic form for the lock to be enforced.

Related Links: 

Time - Customizing Time Entry