If you are going to offer special amenities such as paid cable, phone, utilities, or alarm service, you will need to figure in the monthly cost of these amenities while you figure up the amount of rent you will have to charge. If you are currently occupying the home you plan to rent, add 15-20% to your utility figure when making this estimate. Tenants are not cognizant of the utilities they use if they do not have to pay the bill.