Structural Reform of Social Security
解释社会保障现收现付制如何运作，混合制（现收现付加个人投资账户）如何实施及转型，分析经济收益，并回应行政成本、风险和收入分配等批评。
overnments around the world have enacted or are currently considering fundamental structural reforms of their Social Security pension programs. The key feature in these reforms is a shift from a pure pay-asyou-go tax-financed system, in which taxes on current workers are primarily distributed to current retirees, to a mixed system that combines pay-as-you-go benefits with investment-based personal retirement accounts. Countries as different as Australia, Chile, China, Britain and Sweden have already adopted mixed systems of this type (Feldstein, 1998; Feldstein and Siebert, 2002). In the United States, President Clinton almost proposed such a plan (Elmendorf, Liebman and Wilcox, 2001), and President Bush has made it a major priority for his second term. This paper will first explain how Social Security works now, how a mixed system could work in practice, and how the transition to such a change could be achieved. I discuss the economic gains that would result from shifting to a mixed system. I then turn to the three problems that critics raise about any investment-based plan: administrative costs, risk and income distribution. Finally, I comment on some of the ad hoc proposals for dealing with the financial problem of Social Security without shifting to an investment-based system.