When an approver denies or makes a change to a timesheet, etc, the employee should get an email notification containing the nature and/or reason for the action.
Examples:
“Your timesheet for [DATE] has been edited. Please review your timesheet at [LINK].”
“Your timesheet for [DATE] has been returned to you for corrections. Reason: [message the approver types into a text edit box]. Please correct and resubmit your timesheet at [LINK].”