all the improvements since you purchased the house are added to the cost basis in the year of sale....
a few exceptions
- you can't 'double dip' - if you expensed some of the items while the properrty was rented, you can't also add it to the cost basis.
- another form of double dipping, for example, is you owned the home long enough that you replaced the roof twice... you can't add both times to the cost basis.
