Yes, you do need to enter it as a fixed asset in TurboTax. You will enter it as Tools, Machinery, Equipment, Furniture and then Trailers and Trailer-Mounted Containers. You may also just see the option for General Purpose Tools, Machinery and Equipment if you are using the Business version of TurboTax. TurboTax will suggest a depreciation figure for the previous years based on the date you put the trailer into service. TurboTax will calculate the current and future year depreciation based on the cost and date put into service that you enter.