Yes, you need to have a type of ledger or book that has a listing of all the costs of the asset and improvements, including the purchase price, that will be added together to determine the adjusted basis going into the capitalization of the asset. Once you get a total, then you have an asset cost and are ready to set up depreciation
Please refer to the following link for Basis of Assets assistance from IRS Pub 551:
IRS Publication 551
Please refer to the following link for information about Residential Rental Property:
IRS Publication 527
