First American CoreLogic, a real estate research company, recently released data on negative equity mortgages for the third quarter of 2009. The situation is stark. Nearly one in four U.S. mortgages (23%) is currently underwater, with the borrower owing more than the property is currently worth. According to First American, when mortgages "near" negative equity are tallied, the total number of mortgages near or currently underwater is around 14 million- "nearly 28 percent of all residential properties with a mortgage nationwide."

Being underwater does not necessarily mean that a borrower is at risk of default. Although foreclosures and payment delinquencies are currently at record levels nationwide in the wake of the popped real estate bubble, most borrowers facing negative equity continue to make their mortgage payments. While being underwater "is the best predictor for loan defaults," according to Sam Khater, economist with First American, "if you have your job and don’t encounter economic shock, you’ll most likely keep paying on your home."

But should you keep paying if you're underwater? Brent White, an Associate Professor of Law at the University of Arizona has examined the situation, and argues in a recent discussion paper that homeowners "should be walking away in droves." According to White, millions of homeowners "could save hundreds of thousands of dollars by strategically defaulting on their mortgages."

Such a strategic move comes with consequences for the borrower- most notably a negative impact on one's credit score. This has a quantifiable cost, but White states that "a few years of poor credit shouldn’t cost more than few thousand dollars," and notes that individuals can rebuild their credit rating over time, and can "plan in advance for a few years of limited credit."

Such costs are, argues White, "minimal compared to the financial benefit of strategic default." White makes use of the hypothetical example of a California couple purchasing an average priced ($585,000), averaged sized home in 2006 to demonstrate the case for default:

"Though they still owe about $560,000 on their home, it is now only worth $187,000. A similar house around the corner from Sam and Chris recently listed for $179,000, which, with a modest 5% down, would translate to a total monthly payment of less than $1200 per month – as compared to the $4300 that they currently pay. They could rent a similar house in the neighborhood for about $1000. Assuming they intend to stay in their home ten years, Sam and Chris would save approximately $340,000 by walking away, including a monthly savings of at least $1700 on rent verses mortgage payments... If they stay in their home on the other hand, it will take Sam and Chris over 60 years just to recover their equity"

White argues that in such cases, borrowers are better off taking a short-term hit to their credit, and strategically defaulting to escape a long-term, crushing financial burden. By staying in the home, borrowers are taking money that could otherwise be saved for retirement or used for other purposes, and throwing it away to service a liability that is unlikely to show positive equity in their lifetime.

Such advice seems most likely to appeal to those upside-down in particularly hard-hit areas of the country, including California, Florida, Nevada and Arizona. However, as noted, most homeowners are sticking it out, and continuing to pay their mortgages. According to White, many who might otherwise make such a decision avoid doing so due to "fear, shame, and guilt," sentiments which are "actively cultivated" by the government and financial industry to keep homeowners from walking away.

It remains to be seen if underwater borrowers will overcome fear of the consequences and take White's advice to strategically default. Mortgage lenders most likely hope that his ideas remain firmly in the minority- as one mortgage executive stated in comments reacting to White's report, the argument for strategic default is "incredibly irresponsible and misinformed," and, if widely embraced, has the potential to "'tear apart the very basis' upon which mortgage lending rests". Losing otherwise performing mortgages to strategic default, whatever the economic sense for borrowers, could be yet another blow to an already reeling industry.