When Allow insufficient balance is unticked on a leave type and an employee applies for leave but doesn't have enough hours, they will receive a message saying this and won't be able to save the application. They will need to modify the application, e.g. reduce the hours or change the dates.
There can be two instances when the employee won't receive this message:
The employee edits an existing leave application (e.g. increases the hours). If Check Balances is not selected as part of the process, the system may allow the leave to be applied for.
If Payroll is offline when the leave application was entered. That is the connection between MicrOpay Evo and ESS is down, then ESS will allow leave applications to be saved without checking the leave balance.
Any time a Leave Application exceeds the employee's balance, the manager or approver will see an insufficient balance message on the application and can decline it.