FactCheck.org, a project of the Annenburg Public Policy Center, wrongly attacked a number of prominent Democrats for correctly pointing out that Social Security does not contribute to the deficit. The people attacked included New York Senator Charles Schumer, Senate Majority Whip Richard Durbin, and President Obama’s Budget Director Jacob Lew.

This point should be pretty straightforward. Under the law, Social Security is financed by a designated tax, the 12.4 percent payroll that workers pay on their first $107,000 of income each year. The money raised through this tax is used to pay benefits. Any surplus is used to buy U.S. government bonds. All funding for the program comes either from this tax or from the bonds held by the program’s trust fund. (The Social Security system is also is credited with a portion of the income tax paid on Social Security benefits.)

Social Security is prohibited from spending any money beyond what it has in its trust fund. This means that it cannot lawfully contribute to the federal budget deficit, since every penny that it pays out must have come from taxes raised through the program or the interest garnered from the bonds held by the trust fund.

The one exception to this rule is the roughly $120 billion being credited to the Trust Fund in 2011 to offset the lost payroll tax revenue due to the 2 percentage point reduction in the payroll tax. Apart from this special 1-year exception approved by Congress at the end of last year, Social Security is literally prohibited under the law from adding to the deficit.

FactCheck argues that Social Security will contribute to the deficit because it will be drawing on the interest on the bonds that it holds beginning in 2016 and later will begin selling these bonds. This would be like claiming that Peter Peterson, the Wall Street investment banker and vociferous proponent of cutting Social Security, is contributing to the deficit if he sells a billion dollars in government bonds to finance his anti-Social Security agenda.

In both cases the government would need someone to buy up the bonds to replace the bonds that were already sold. However, this is just a redistribution of the debt. The decision by the Social Security trust fund to sell its bonds no more increases the debt of the U.S. government than the decision by Peter Peterson to sell his bonds.

FactCheck’s confusion probably stems from its reliance on figures for the “unified budget.” This budget adds in the annual surplus or deficit from Social Security.

However, every single budget document put out by the government also includes the “on-budget” budget that treats Social Security as the distinct program it is under the law. This budget would show that Social Security has no effect on the deficit (except due to the payroll tax cut for 2011), since it is a self-financed program.

Obviously Senators Schumer and Durbin and Mr. Lew were referring to the on-budget budget. It is hard to believe that Factcheck did not understand this basic fact about the U.S. budget. They were right and FactCheck is wrong.

Social Security does not contribute to the budget deficit. That is the law.