The Internal Revenue Service has increased the optional standard mileage rates for the final six months of 2011 to 55.5 cents per mile, up from 51 cents per mile set in January, 2011. Taxpayers may use the optional standard rates to calculate the deductible costs of operating an automobile for business and other purposes.

In response to this year’s increase in gasoline prices, IRS made this special adjustment for the final months of 2011.This rate increase will be effective for all business miles driven from July 1, 2011, through Dec. 31, 2011. This comes at a time when fuel costs are on the decline.

The new six-month rate for computing deductible medical or moving expenses will also increase to 23.5 cents a mile, up from 19 cents for the first six months of 2011.

Unlike this standard mileage rate, the rate for providing transportation services for charitable organizations is set by statute, not by the IRS. It will remain at 14 cents a mile.