How the employee is allowed to register their own sick leave.

There are settings that determine how the employee is allowed to register their own sick leave.

Go to "System Settings → Modules → Sick Leave → Availability." If you set "Allow employees to register their own sick leave" to "Yes," they can register it on "Today's date."

If you also set "Allow employees to register leave retroactively " to "Yes," they can choose a date in the past. It should be noted that the latter setting only allows retroactive registration up to the last completed sick leave in their history.