if you reinvest the selling price as down payment or in the event of a trade both lower the amount you are left to depreciate. but a reinvestment of the selling price negates capitol gains tax somehow through the tax laws. we did this and never paid capital gains tax on the selling price. i have a very reputable and knowledgeable accountant doing my corporate taxes. i cannot say how this is done and the tax may be canceled out by something else in the equation. all i know is we didnt pay it or get in trouble for it and the firm is far from doing anything that is not legal.