The Internal Revenue Service has reduced the business mileage reimbursement rate for one half of a cent to 53.5 cents from 54 cents. The new rate went into effect on Jan. 1.

The I.R.S. also dropped the rate for medical or moving expenses to 17 cents from 19 cents. The I.R.S. set the rate for miles drive in service of charitable organizations at 14 cents per mile.

A year ago, the I.R.S. lowered the deductible mileage rate to 54 cents per mile for business miles in 2016 down from 57.5 cents in 2015.

The standard mileage rate for business is based on an annual study of the fixed and variable costs of operating a vehicle. The rate for medical and moving purposes is based on the variable costs. Taxpayers always have the option of calculating the actual costs of using their vehicle rather than using the standard mileage rates, according the agency.