When it comes to income taxes, every deduction is important; especially if you're self-employed. However, mileage can also be deducted for medical trips and charitable services if you meet certain qualifications. Car mileage is a deduction that is often missed for the simple reason that the filer is unsure how to calculate the mileage. The key to calculating mileage for taxes is keeping records throughout the year and knowing how to use them for a deduction when it comes time to file your taxes.
Step 1
Keep a log book in your vehicle throughout the year. Mileage for taxes is tracked from January 1 through December 31, and unless you use your car exclusively for business, you should write down the beginning mileage, the ending mileage and the purpose of the trip each time you use of your car for business.
Step 2
Subtract the beginning mileage from the ending mileage for each trip to determine the miles driven for that trip. Do this on a regular schedule, such as once a week or once a month, to maintain the ease of tracking total mileage used.
Step 3
Add the total miles driven after the end of the year to determine your total mileage for taxes. Multiply this number by the allowable deduction for vehicle use.
Step 4
Enter this amount in the mileage deduction line on the tax form you are using, such as Schedule C for businesses (or when asked for the amount on an online tax program).