How do I enter my self-employment business mileage? I am using the free and simple form of TurboTax.

[LinaJ2018]

For self-employment income and expenses, you would either need a TurboTax Deluxe or TurboTax Self-employed online edition.  The free edition does not support.  

If you have any business related expenses, you would need an upgrade to the Self-employed edition.  You would follow prompts to enter your information and the program will prompt you to an upgrade. 

The TurboTax Deluxe only support situation when you only have self-employed income without any related expenses.