No one can accuse the Internal Revenue Service of sleeping on the job.
You may remember a blog post of mine dated June 30th, 2008 called "IRS Standard Mileage Rate Change" in which I noted how quickly the IRS reacted to rising gas prices and increased their standard mileage rate change, effective July 1, 2008, from 50.5 cents to 58.5 cents per mile. This generally allowed employers to avoid reporting or withholding from increased reimbursements to employees for the remainder of the year.
As quickly as the IRS reacted to the rising gas prices, it has reacted just as quickly to the recent fall. Through IRS Rev. Proc. 2008-72, the IRS has lowered the standard mileage rate to 55.0 cents per mile for 2009. In addition, the standard mileage rate for medical or moving and medical expenses has been decreased from 27 to 24 cents per mile, and the rate for charitable purposes remains at 14 cents per mile.
According to IRS News Release IR-2007-192, the rates are based "on an annual study of the fixed and variable costs of operating an automobile . . . [and of] medical and moving purposes."