Capital Gains

[Mark Risley]

Hello BP community!

I have a client that owns two properties and is planning on possibly selling them both and using the money to buy their dream home. 

They are a married couple that both bought their homes before meeting each other. They currently like in "her' house, and his son lives in "his" house. They have never claimed "his" property as a rental on their taxes nor had any type of formal lease. He has not occupied the property two of the last 5 years personally, but his family has. How would this affect him as far as capital gains? Is there a loop hole or something he can use to avoid getting hosed?

Any input would be greatly appreciated!