Deductions & credits
TurboTax will give you a message saying "Actual expenses vs. standard mileage rate" after you have entered your actual expenses versus your business mileage.
TurboTax will recommend using the method which yields the highest deduction.
It does, however, give you the option to select another method. Please make sure you have selected the standard mileage rate if that yields a better result for your situation.
Self employment tax is calculated on your overall net income from your Schedule C business, or total income less total expenses. If your net income is positive, you will be subject to Self Employment(SE) income. SE tax is computed at 12.4% for Social Security and 2.9% for Medicare.
The following provides more details of how the Self Employment tax is calculated.
