The annual cost of Social Security benefits represented 4.4 percent of GDP in 2008 and is projected to increase to 6.2 percent of GDP in 2034, and then decline to about 5.8 percent of GDP by 2050 and remain at about that level. The projected 75-year actuarial deficit in the combined Old-Age and Survivors and Disability Insurance (OASDI) Trust Fund is 2.00 percent of taxable payroll, up from 1.70 percent projected in last year's report. This increase is due primarily to the recession, slightly lower estimates for real GDP after the economy recovers in 2015, and faster reductions in mortality rates. Although the combined OASDI program passes our short-range test of financial adequacy, the Disability Insurance Trust Fund does not; DI program costs have exceeded tax revenue since 2005, and trust fund exhaustion is 

projected for 2020. In addition, OASDI continues to fail our long-range test of close actuarial balance by a wide margin. Projected OASDI tax income will begin to fall short of outlays in 2016, and will be sufficient to finance 76 percent of scheduled annual benefits in 2037, after the combined OASDI Trust Fund is projected to be exhausted.

Social Security could be brought into actuarial balance over the next 75 years with changes equivalent to an immediate 16 percent increase in the payroll tax (from a rate of 12.4 percent to 14.4 percent) or an immediate reduction in benefits of 13 percent or some combination of the two. Ensuring that the system remains solvent on a sustainable basis beyond the next 75 years would require larger changes because increasing longevity will result in people receiving benefits for ever longer periods of retirement.