The sale of the rental might be $225,000 and the duplex might cost $500,000.  The part of the duplex being rented out might be valued at $250,000, so the new investment property is valued higher than the sale price of the rental.  So if all of the proceeds are used to purchase the duplex would there be any boot?  Would some of that down payment need to be allocated to the personal half of the duplex, and create boot?  Am I thinking about this the right way?