The rates are determined by the IRS from a calculation of fixed and variable costs of owning and operating a vehicle. The rate is released annually by the IRS per Rev. Proc. 2010-51.
Taxpayers may still use the actual costs of operating the vehicle as opposed to the standard mileage deduction. The exception is if the business has used a depreciation method on the vehicle. In this case they must use the actual costs of operating the vehicle.
Along with the IRS many companies use the standard mileage deduction for employee expense report. If you have any questions on the impact to your businesses accounting then we are here to help.