By Jason Watson (Google+)
Mileage is one of the most often deducted expense, and therefore it is one of the most scrutinized records. First, you need to prove you own the vehicle(s). Next, you need to keep track of your beginning and ending odometer readings. It is a good idea to make copies of service invoices such as Jiffy Lube since these companies record odometer readings. Lastly, you need to keep track of the date, the business miles driven and the business connection.
We strongly suggest using an app for your smartphone that can track all this with GPS technology. Many of these apps will then email you a CSV file detailing all your miles. Very nice!