Accurately tracking vehicle mileage is often overlooked in small business accounting and tax preparation. Either mileage is underreported due to lack of records or a fear of being audited, or it's over-reported, also due to lack of records, or a "I know how much I drove" attitude.

Although it's best if taxpayers have a small notebook in the car to record actual odometer readings each time a business trip is made, this is cumbersome, and most people don