Absence Management question

I have an urgent question:

If an employee is awarded a starting balance of lets say 25 days of leave. Questions are:

- If they have used up those 25 days, does the system even allow them to submit any further absence requests? Or does it just say that you have used up all your leave balance?

- Say they used up 24 days, and they applied the last leftover of one day of absence. It was still sitting with the manager for approval. Would the system disallow to submit say one more day of absence (with the one last day pending approval), or would it recognise that the last day is impending approval, and therefore not allow employee to submit a leave request for that day?