In order to take advantage of the up-to-$500,000 exclusion of gain (or up-to-$250,000 if you file a tax return as a single taxpayer) the house you sell has to be your "principal residence". Under most circumstances, we do not need a legal definition of this concept. "This is my house, and I have lived here for many years; what's the problem." But as we all know, life is often not that simple. And, unfortunately, there is no definition provided in the Tax... [read more]