if this is the first year the rental vehicle is being used in your business you can choose between the two methods - standard mileage rate and actual costs. if you use actual costs that's the method you must use for all future years you use the vehicle. if you choose the standard mileage rate the first year, you get to choose either method in future years. regardless of method, you are only allowed to deduct the portion of costs (other than tolls and parking for business) that bear the ratio of business mileage to total mileage. you must maintain records for the mileage. in addition when leasing/renting a vehicle there is an annual lease inclusion amount published by the IRS (when actual costs are used)
