The kind of taxes that do adjust your gains would be transaction taxes, not income taxes. For example, in the county where I live in New York state, the seller is charged 0.5% transfer tax and the buyer is charged 0.75% transfer tax that goes to the county, not the state or IRS. There is also a $50 fee to record a new deed and mortgage, and a mortgage tax of 0.25% of the mortgage (if there is a mortgage) that goes to the county as well. Those are adjustments to the capital gains because they are considered additions to the purchase price or reductions in the sales price.
