Whether banks can and will pursue deficiency judgments depends on many factors, including what state the borrower lives in and whether there's a second mortgage or other liens. But if borrowers ignore the possibility of deficiencies, it could haunt them.

"Once they have a judgment, they can pursue you anywhere," said Richard Zaretsky, a board-certified real estate attorney in West Palm Beach, Fla. "They can ask for financial records, have your wages garnished and, if you fail to respond, a judge can put you in jail."

In the case of foreclosure, lenders can pursue deficiencies in more than 30 states, including Florida, New York and Texas, according to the U.S. Foreclosure Network, an organization of mortgage law firms.

Some states, such as California, are "non-recourse" and don't allow deficiency judgments. But, even there, if the original loan was refinanced, some or all of it may be subject to claims. Contact your local tax advisor for answer to your personal situation.