The simplest automobile tax expense situation is one in which a vehicle is used entirely for business. For example, if you have a van used for a delivery service and nothing personal, all expenses associated with the van can be written off. This is known as the exclusive use situation. For many small businesses, however, a vehicle will be used for both personal and business reasons.
Where you use a vehicle for both personal and business reasons, you can only deduct the automobile expenses associated with the business use. Keep in mind that driving to and from work is not considered business mileage, while driving from an office to meet a client is considered business mileage.
There are two methods for determining deductible automobile tax expenses.
The first is a simple calculation known as the standard mileage deduction. The second is the actual expenses method. You can choose whichever deduction provides you with the biggest deduction unless you lease the car. With a lease, you must use the standard mileage deduction.