Bob Pozen knows how to fix Social Security, even after the United States falls off the new fiscal cliff—and the U.S. will fall, on March 1 to be exact, predicts the Harvard Business School senior lecturer and Brookings Institution fellow.

The solution is simple, and it doesn't involve raising taxes, the former MFS Investments chairman told an audience of 800 advisors and wealth managers at the sold-out Investment Management Consultants Association (IMCA) conference in New York on Monday.

What Pozen, the author of six books, proposes instead is increasing the progressivity of the tax code. He believes that going from the current wage indexing of initial benefits to a system of price indexing would provide Social Security the reform needed to wipe away its $8.6 trillion present-value, 75-year deficit.