Change from personal to business use
Line 12: If you converted your vehicle during the year from personal to business use or from business to personal use and you do not have mileage records for the time before the change to business use, enter the total number of miles driven after the change to business use.
Line 13: Do not include commuting miles on this line; commuting miles are not considered business miles. See line 15 instructions for the definition of commuting.
Line 14: If you entered on line 12 the total number of miles driven after the change to business use, multiply the percentage you calculated by the number of months you drove the vehicle for business and divide the result by 12.
Line 15: Enter your average daily round-trip commuting distance. If you went to more than one work location, calculate the average.
Commuting is generally travel between your home and a work location. However, travel that meets any of the following conditions is not commuting:
You have at least one regular work location away from your home and the travel is to a temporary work location in the same trade or business, regardless of the distance. Generally, a temporary work location is one where your employment is expected to last one year or less. For more information, see Itemized deductions and review the 2017 IRS Publication 463, Travel, Gift and Car Expenses .
The travel is to a temporary work location outside the metropolitan area where you live and normally work.
Your home is your principal place of business under IRC § 280A(c)(1)(A) (for purposes of deducting expenses for business use of your home) and the travel is to another work location in the same trade or business, regardless of whether that location is regular or temporary and regardless of distance.
Line 16: If you do not know the total actual miles you used your vehicle for commuting during the year, calculate the amount to enter on line 16 by multiplying the number of days during the year that you used each vehicle for commuting by the average daily round-trip commuting distance in miles. However, if you converted your vehicle during the year from personal to business use or from business to personal use, enter your commuting miles only for the period you drove your vehicle for business.