A designated vehicle for your business may qualify as a deduction for its entire cost of ownership and operation (subject to limits discussed later). However, if you use the vehicle for business and personal purposes, you may only deduct its use for business purposes.
You can generally figure the amount of your deductible car expense by using one of two methods: the standard mileage rate method or the actual expense method. If you qualify to use both methods, you may want to figure your deduction both ways before choosing a method to see which one gives you a larger deduction.
To add mileage/vehicle expenses on Schedule C
1) Enter the return, select Add Form + under Federal Return in the sidebar navigation
2) Search Schedule C Profit or Loss from Business in the sidebar search engine
3) Select Add New
4) You will need to make all the proper inputs and specifically scroll down to Expenses, on line 9, indicate Yes if there is a Car and/or Truck Expense on the Schedule C. You will need to Save and Continue to get to the next page
5) Select +Add New on the Asset Basic Information Page, and complete the following pages
6) Complete the Automobile Listing page
Here is where to indicate the mileage entries to expense.