I often get the question, "What should I do to document my vehicle mileage for tax purposes?" The following information should be provided to document your business mileage:
1) Maintain a log that contains the following information: Date, Business Purpose of Trip, Total miles driven, commute distance, personal mileage, and finally business miles.
2) Maintain maintenance records that reflect your milage. The log should coinside with the maintenance records and act as a verification tool.
Your record does not have to be maintained all year. It can be maintained for a typical period of time (usually a month or more) and then this period can be applied to the entire year if the time period is representative of the whole year.
The business purpose is important and should be sufficeiently detailed with the name of the person you met with, what business you conducted and where.
Rember that you must always deduct off your comute from the total mileage for the day.