The tax shelter was one of corporate America's biggest hidden profit centers in recent years. Shelters have become so lucrative that some experts estimate as much as $50 billion is lost to the U.S. Treasury each year. And ordinary taxpayers wind up f... (more)ooting the bill. FRONTLINE correspondent Hedrick Smith provides an inside look at how big corporations and wealthy individuals cut their taxes with intricate, hidden, and abusive tax shelters and investigates the role of blue chip accounting firms in these secret deals.