  Using a lifecycle framework with Epstein-Zin (1989) utility and a
mixed-integer optimization approach, we compute the optimal age to claim Social
Security benefits. Taking advantage of homogeneity, a sufficient statistic is
the ratio of wealth to the primary insurance amount (PIA). If the investor's
wealth to PIA ratio exceeds a certain threshold, individuals should defer
Social Security for at least a year. The optimal threshold depends on mortality
assumptions and an individual's utility preferences, but is less sensitive to
capital market assumptions. The threshold wealth to PIA ratio increases from
5.5 for men and 5.2 for women at age 62 to 11.1 for men and 10.4 for women at
age 69. Below the threshold wealth to PIA ratio, individuals claim Social
Security to raise consumption. Above this level, investors can afford to fund
consumption out of wealth for at least one year, and then claim a higher
benefit.
