Let me add a little bit of detail then. My mileage split between business and personal comes up to 65%. If I enter into TurboTax that my sale date was end of February of 2021, then it calculates my % business use as 65% x (2months/12months) = 10.8% and the entire 100% depreciation that was taken the first year goes away since it believes my business use has dropped below 50% in a single year. If, however I enter into TurboTax that my sale date was beginning November of 2021, it calculates my % business use at 65% x (10 months/12 months) = 54.2%. So it seems like the calculation in Turbotax is: (i) determining fraction of miles to total miles, and then (ii) multiplying that resulting amount by the number of months the vehicle was used during the year divided by 12 months. This is resulting in a differential business use depending upon when the vehicle was disposed of during the year. I can't find any publication anywhere that states this is a valid way of calculating business use in the context of a business asset sale. Does anyone have a reference on this?
