For what purpose?
Are you self-employed?
If so it goes on your Schedule C with your other business expenses.
Are you entering mileage for driving to and from medical appointments, etc.?
Go to Federal>Deductions and Credits>Medical>Medical Expenses
Are you entering mileage for driving as a volunteer for a charitable organization
Federal>Deductions and Credits>Charitable Donations>Donations to Charity
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**