What is the tax trap of renting out a home before selling it?

Renting out a home before selling it can cost you a capital gains exclusion normally available on a primary residence, since that exclusion generally requires living in and owning the home for a set period within the years before the sale. Once a home has been a rental too long, some of the gain can become taxable in a way it would not have been from a straight sale. This is a tax question, not a real estate one, and deserves a CPA. Joel Boss can point you to one.