Don't forget to adjust your travel reimbursement amount, if you tie it to the Internal Revenue Service mileage rate. Beginning Jan. 1, the standard mileage rate for cars is 54.5 cents per mile. That's "up 1 cent from the rate for 2017," the IRS points out on its website at www.irs.gov/newsroom/standard-mileage-rates-for-2018-up-fromrates-for-2017.