Mileage for what exactly:  Self-employment work?  Charity?  Medical? Moving?

If you are self-employed then this can be deducted under Vehicle expenses on the business activity (Schedule C), if you are an employee there is no deduction allowed for employee business expenses after December 31, 2017, due to the Tax Cuts and Jobs Act (TCJA).

The Form 2106 will be used by Armed Forces reservists, qualified performing artists, fee-basis state or local government officials, and employees with impairment-related work expenses. Due to the suspension of miscellaneous itemized deductions subject to the 2% floor under section 67(a), employees who do not fit into one of the listed categories may not use Form 2106. IRS Publication 463

For self-employment purposes follow these steps to enter your vehicle for your business.

1. Down the left side, click Federal.
2. Click on Wages & Income.
3. Under Your income, click on Edit/Add to the right of Self-employment income.
4. Click on Edit next to the business name.
5. To the right of the vehicle expenses, click Edit.
6. Under Vehicle Summary, click Edit to edit the entries.  Click Delete to delete the entries.