The IRS sets an optional standard mileage rate for business driving each year, based on costs of operating a vehicle. The 2021 mileage rate is 56 cents a mile driven for business use, down 1.5 cents from the 2020 rate. The IRS also sets two other driving rates. The other 2021 driving rates are: 16 cents a mile for medical purposes and for moving expenses for active duty military 14 cents a mile for driving in service of charitable organizations