This paper describes how three money’s worth measures – the benefit-to-tax ratio, the internal rate of return, and the net present value – are calculated and used in analyses of social security reforms, including systems with privately managed individual accounts invested in equities. Declining returns from the U.S. social security system prove to be the inevitable result of having instituted an unfunded (pay-as-you-go) retirement system that delivered $7.9 trillion of net transfers (in 1997 present value dollars) to people born before 1917, and will deliver another $1.8 trillion to people born between 1918 and 1937. But young and future workers cannot necessarily do better by investing their payroll taxes in capital markets. If the old system were closed down, massive unfunded liabilities of $9-10 trillion would still have to be paid unless already accrued benefits were cut. Alternative methods of calculating these accrued benefits yield somewhat different numbers: the straight line calculation is $800 billion less than the constant benefit calculation we propose as the benchmark. Using this benchmark in a world with no uncertainty, we show that privatization without prefunding would not increase returns at all, net of the new taxes needed to pay for unfunded liabilities. These new taxes would amount to 3.6 percent of payroll, or about 29 percent of social security contributions. Prefunding, implemented by reducing accrued benefits or by raising taxes, would eventually increase money’s worth for later generations, but at the cost of lower money’s worth for today’s workers and/or retirees. Computing money’s worth when there is uncertainty is much more difficult unless four conditions hold, namely optimization, time homogeneity, stable prices, and spanning. Under these conditions, the diversification of social security investments into stocks and out of bonds has no effect whatsoever on money’s worth when it is properly adjusted for risk: a dollar of stock is worth no more than a dollar of bonds. When spanning fails, diversification can raise welfare for constrained households, but the exact money’s worth must depend on specific assumptions about household attitudes toward risk. Calculations like those of the Social Security Advisory Council that attribute over $2.85 of net present value gain to each $1 shifted from bonds to stocks completely overlook the disutility of risk. By contrast, we estimate that a 2 percent of payroll equity fund carved out of social security would increase net present value by about 59 cents per dollar of bonds switched into equities, instead of $2.85. When the likely reductions in income and longevity insurance are factored in, the net advantage of privatization and diversification is substantially less than popularly perceived.
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Paper
John Geanakoplos & Olivia S. Mitchell & Stephen P. Zeldes, 2000.
"Social Security Money's Worth,"
NBER Working Papers
6722, National Bureau of Economic Research, Inc.
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References listed on IDEAS Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.:
Martin Feldstein & Jeffrey B. Liebman, 2001.
"Social Security,"
NBER Working Papers
8451, National Bureau of Economic Research, Inc.
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Other versions:
Feldstein, Martin & Liebman, Jeffrey B., 2002.
"Social security,"
Handbook of Public Economics,
in: A. J. Auerbach & M. Feldstein (ed.), Handbook of Public Economics, edition 1, volume 4, chapter 32, pages 2245-2324
Elsevier.
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