If my vehicle is used almost 100% for business, can I just track the personal miles to be subtracted out of the total miles?

[stk]

Business use is as a real estate agent, so the vehicle is always used for business with the exception of miles driven for personal reasons.  I work out of the home on a regular basis, so no commuting miles.   For supporting documentation, can I just show the beginning & ending miles to calculate the total miles driven, and then track & subtract out the personal miles driven from the total?

[HelenaC · Accepted solution]

No. You can only deduct mileage if you keep a written log of your business miles otherwise you can't deduct mileage. Per IRS, you have to have adequate evidence. See https://www.irs.gov/publications/p463/ch05.html .

The IRS considers adequate evidence as a log of  "who, what, when, and where" which may include the following:

• The cost of the car and any improvements,
• The date you started using it for business,
• The mileage for each business use,
• The total miles for the year.
• Date of the expense.
• Your business destination.
• Business purpose for the expense. 

If you are self-employed (Schedule C), enter/edit your vehicle's mileage:

• Log on to TurboTax and click on the orange button, Take me to my return.
• Type vehicle expenses, self-employed business in the search/find box and click search.
• Click on Jump to vehicle expenses, self-employed business.
• Edit your business.
• At the 'Your xxxx Business' screen, scroll down to Business Expenses.
• Click start/update next to Business Vehicle Expense.
• Continue with the onscreen interview until you get to the 'How Do You Want to Enter Your Mileage for your vehicle'.  

See the screenshot below.