Hi Sankarsan,
If Employees comes at 8:45 am and left 17:45pm then, total working hours will be 8.75 hours and shortfall will be 0.25 hours. Because start time should count from 9:00 am.
But, If Employees comes at 9:45 am and left 18:45pm then, total working hours will be 9.00 hours and no shortfall. Because start time is after 9:00 am.
Best Regards,
Deepak