Some mortgages are not non-recourse, so you could be forced into bankruptcy. Either way, your credit is going to take a big hit, which may mean you're stuck wherever you moved to, since many landlords will avoid renting to people with recent forclosures or bankruptcies. (Probably a good idea to move before you default). A lot of people are uncomfortable defaulting on a debt if they have the ability to pay, even if it's the smartest move economically.