Reacting to rising gasoline prices, the Internal Revenue Service has announced an increase in the optional standard mileage rates for the last six months of 2008. Effective July 1, 2008 through December 31, 2008 the rates for business miles and medical and moving expense mileage will increase by 8 cents. The rate for providing services for charitable organizations is set by statute, not the IRS. That amount will not be changing.