What are tax shelters? How can you tell the difference between legitimate and illegitimate tax shelters? How do abusive tax shelters affect the honest citizen's tax return? Here are answers to these and other questions.

Although the government thought it had shut down bogus tax shelters in the 1970s and 1980s, regulators and lawmakers were shocked by their proliferation in the 1990s. Here, tax attorney Harold Handler, former and current IRS officials Charles Rossotti, Larry Langdon and Mark Everson, and Sen. Carl Levin (D-Mich.) explain the characteristics of 1990s tax shelters that made them qualitatively different from previous incarnations, and how blue-chip accounting, law and investment brokerage firms drove the transactions.

Some tax experts argue that in the aftermath of Enron and other corporate scandals, companies will be less likely to use devices such as tax shelters to pump up their bottom line. Others maintain that the current lull in shelter activity is due to the current economic downturn and that when the economy rebounds the widespread use of tax shelters will reappear. Here are the views of former and current IRS officials Charles Rossotti, Larry Langdon and Mark Everson; Senators Charles Grassley (R-Iowa) and Carl Levin (D-Mich.), and former Assistant Treasury Secretary Pamela Olson.

"Tax Me If You Can" producer and director Rick Young reveals how FRONTLINE's investigation into tax shelters led him to the sewers of Bochum, Germany.