The Internal Revenue Service last week set the deductible rate that workers can claim next year for using personal vehicles for business at 44.5 cents a mile. That's less than the temporary 48.5-cents-per-mile that the IRS put in place for the last four months of 2005. This year's base rate was 40.5 cents a mile. The rate next year for figuring deductible medical or moving expenses will be 18 cents a mile.