Business road warriors will get a slightly lower mileage tax deduction in 2017. The Internal Revenue Service announced Tuesday the new national business mileage deduction rate will be 53.5 cents per mile, down a half-cent from the current 54 cent deduction. It’s the fifth time in the last 16 years the rate has fallen instead of rising for U.S. business drivers, which goes into effect Jan. 1, 2017. Declining fuel prices, which were largely offset by rising vehicle insurance and maintenance costs, contributed to the slight decrease, according to Runzheimer, the firm that provides data the IRS uses to calculate the rate.