DEAR BOB: Regarding that $250,000 ($500,000 for a married couple filing jointly) home-sale tax break, what about the taxes that would have been due on deferred gains from sales of prior principal residences? My wife and I bought and sold a total of four principal residences over the years, for a total deferred capital gain of about $300,000. Will that amount reduce our $500,000 exemption when we sell our current home?  more...