WASHINGTON – The IRS announced the optional standard mileage rate for business use of a vehicle is unchanged from the rate announced in July 2011, at 55.5 cents per mile.

The IRS said the standard mileage rate for business is based on an annual study, conducted by Runzheimer International, of the fixed and variable costs of operating an automobile.

The medical and moving rates have been reduced by 0.5 cents per mile, to 23 cents. The rate for charitable organizations is 14 cents per mile.

The rates will go into effect Jan. 1, 2012.