Taxpayers may use the optional standard rates to calculate the deductible costs of operating an automobile for business, charitable, medical or moving purposes.

The rate will increase to 58.5 cents a mile for all business miles driven from 1st July, 2008, through 31st December, 2008.

This is an increase of eight (8) cents from the 50.5 cent rate in effect for the first six months of 2008, as set forth in Rev. Proc. 2007-70.

In recognition of recent gasoline price increases, the IRS has made this special adjustment for the final months of 2008. The tax authority normally updates the mileage rates once a year in the fall for the next calendar year.

"Rising gas prices are having a major impact on individual Americans. Given the increase in prices, the IRS is adjusting the standard mileage rates to better reflect the real cost of operating an automobile," explained IRS Commissioner Doug Shulman, adding that:

"We want the reimbursement rate to be fair to taxpayers."

While gasoline is a significant factor in the mileage figure, other items enter into the calculation of mileage rates, such as depreciation and insurance and other fixed and variable costs.

The optional business standard mileage rate is used to compute the deductible costs of operating an automobile for business use, in lieu of tracking actual costs. This rate is also used as a benchmark by the federal government and many businesses to reimburse their employees for mileage.

The new six-month rate for computing deductible medical or moving expenses will also increase by 8 cents to 27 cents a mile, up from 19 cents for the first six months of 2008. The rate for providing services for charitable organizations is set by statute, not by the IRS, and remains at 14 cents a mile.

Taxpayers also have the option of calculating the actual costs of using their vehicle rather than using the standard mileage rates.