Actually both are wrong. The credit score will drop anywhere from 50-200 pts depending on how much other debt you have. Additionally, each state has its own laws regarding paying back the difference. In Texas, you are responsible for the difference between what you owe and the fair market value. So if you owe 200K, the home is valued at 200K, and the bank sells for 190K, you do not owe anything. In some states, you might owe the 10K, but not all.