The rate is determined by the GSA apparently based on actual costs for driving.
In 2016 it is down to 19 cents a mile but the cost of fuel is down dramatically as well so it worked out great!
The Medical/Moving deduction back in 2015 was listed at $0.23 or twenty-three cents a mile.
In that year it was a half of a cent higher at 23.5 cents per mile for medical mileage.
That is not bad but in 2013 it was 24 cents per mile, which was a half cent higher.
The rate for Medical / Moving mileage is down from 2013 and 2014 the rate for 2014 was $0.23.5 or twenty-three and a half cents per mile.
Here is some info on the 2013 medical mileage rate.
Let's just guess that you are driving a trip of 50 miles to the specialized medical facility for some treatment once a week. You have to drive home from there as well so the trip is 100 miles a week. That trip x 52 weeks of a year would give you a total of 5,200 miles.
At that rate multiplied by twenty three cents per mile you would get a deduction of $1,196.00 for the year. That pays for a lot of gas for your car!
So use the mileage method if you can. Get more info at the IRS §214.