The Cash Due Employee is non-cash tips minus cash. It is the amount of money that the house should pay the employee in tips at the end of the shift. If the number is negative, the employee owes that amount to the house.
The employee earns $120.00 in credit tips. She also collects $100.00 in cash. So in this case, the cash due to the employee is $20.00. If you cash out your employees' tips at the end of the night, you would give her $20.00 to cover her tips.
By backend setting, you can also include payouts and payins into this calculation.