Alas, Social Security is an unfunded liability, because all the money working people put into it was stolen by Republicans and Democrats in order to pay for wars and bailouts for mega-rich bankers like Goldman Sachs.
What I am about to tell you might come as a shock, but it is the absolute truth, which you can verify for yourself by going online to the government's annual OASDI and HI reports. According to the official 2010 Social Security reports, between 1984 and 2009 the American people contributed $2 trillion, that is $2,000 billion, more to Social Security and Medicare in payroll taxes than was paid out in benefits.
What happened to the surplus $2,000 billion, or $2,000,000,000,000.
The government spent it.
Over the past quarter century, $2 trillion in Social Security and Medicare revenues have been used to finance wars and pork-barrel projects of the US government.
Depending on assumptions about population growth, income growth and other factors, Social Security continues to be in the black until after 2025 or 2035 under the "high cost" and "intermediate" assumptions and the current payroll tax rate of 15.3% based on the revenues paid in and the interest on those surplus revenues. Under the low cost scenario, Social Security (OASDI) will have produced surplus revenues of $31.6 trillion by 2085.
When I was Assistant Secretary of the US Treasury, Deputy Assistant Secretary Steve Entin worked out a way to put Social Security on a sound basis with the current rate of payroll tax without requiring one cent of general revenues. You can read about it in chapter 9 of my book, The Supply-Side Revolution, which Harvard University Press has kept in print for more than a quarter century. Entin's solution, or a variation of it, would still work, so Social Security can easily be saved within the current payroll tax rate. Instead of acknowledging this incontrovertible fact, the right-wing wants to terminate the program.
Treasury was blocked from putting Entin's plan into effect by the fact that other parts of the government and the Greenspan Social Security Commission had agendas different from ensuring a sound Social Security system.