Social Security Card © Scott Speakes,Corbis

The Social Security trust fund is expected to be exhausted in 2033. After that, there will be enough tax revenue coming in to pay out about 75% of promised benefits. However, just a few changes to the system could prevent these steep benefit cuts. Here are five potential Social Security changes, along with how much of the budget shortfall each would address:

Increase Social Security taxes. Workers currently pay 6.2% of their earnings into the Social Security system up to $113,700 in 2013. If that tax rate was gradually increased to 7.2% by 2036, doing so would eliminate just over half (53%) of Social Security's projected deficit. And if workers and employers each paid 7.6%, it would eliminate the financing gap altogether. Some 69% of Americans support raising their own Social Security taxes by 1%, according to a recent online survey of 2,000 Americans ages 21 and older conducted by the National Academy of Social Insurance (NASI) and Mathew Greenwald and Associates.

Lift the payroll tax cap. For 2013, workers pay Social Security taxes on up to $113,700 of earned income. Individuals who earn more than that don't pay Social Security taxes on the additional income. If this tax cap was gradually eliminated from 2013 to 2022, it would reduce the deficit by 71%. And if the tax cap were increased over five years to include 90% of all earnings (currently about 84% of earnings are covered), it would reduce the financing gap by 30%. This change would affect the 5% of workers whose earnings exceed the cap, and they would receive somewhat higher benefits when they retire. Lifting the payroll tax cap is a popular idea, with 68% of Americans supporting the complete elimination of the cap, NASI found.

Raise the retirement age. The age at which retired workers can collect full Social Security benefits is currently scheduled to increase to 67 for those who were born in 1960 or later. If the full retirement age was further increased to 68 by 2028 it would reduce benefits by about 7% and eliminate 15% of Social Security's funding shortfall. Increasing the full retirement age to 70 by 2050 would reduce benefits by about 21% and the deficit by a quarter. Raising the retirement age is an unpopular idea, with only about a third (37%) of Americans supporting raising the retirement age to 68 and just over a quarter (28%) in favor of increasing the full retirement age to 70.

Means-test benefits. Another potential Social Security change is to reduce or eliminate Social Security benefits for people who have retirement incomes above a certain threshold. For example, if benefits were phased out for retirees with non-Social Security income from $55,000 to $110,000, the deficit would be reduced by 20%. NASI found that 31% of Americans say they would like to means-test Social Security eligibility.

Change the cost-of-living adjustment. Social Security benefits are adjusted for inflation each year based on the Consumer Price Index for Urban Wage Earners and Clerical Workers. If an alternative measure of inflation, the chained CPI-W, were used, that would decrease the annual cost-of-living adjustment by an average of about 0.3 percentage points and reduce Social Security's deficit by 20%. Using chained CPI-W would increase a $1,000 monthly benefit by $27 instead of the $30 boost retirees would get using the current measure. Just under a third (30%) of Americans are in favor of changing this cost-of-living adjustment.

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