The trust funds do not buy bonds. That’s because they do not buy anything. But they do create special pieces of paper which are misnamed “government bonds.” They are misnamed because — unlike other bonds — these bonds were never bought or sold. They are literally IOUs the government writes to itself. For Social Security, they are created on a typewriter. For Medicare, they are created electronically.
Technically, the trust fund bonds represent the cumulative surplus (payroll tax collections minus benefit payments). But these bonds are only important for accounting purposes. They are like bookkeeping entries, without any market value. The annual reports of the Social Security trustees list the yields and maturity dates of these bonds. But the special-issue bonds are not the same as the bonds held by the public. They are not part of the official outstanding debt of the U.S. government. They cannot be sold on Wall Street or to any foreign investors. And they cannot be used to pay benefits.
The technical issuer of the bonds (the U.S. Treasury) and the holder of the bonds (the Social Security trust fund) are both agencies of the U.S. government. Moreover every asset of the trust fund is a liability of the Treasury. Summing over both government agencies, the balance is zero.
For Social Security, the trust fund’s special issue bonds are paper certificates held in government filing cabinets in Parkersburg, W.Va. If a fire were to burn down the building tomorrow, or if thieves were to take the filing cabinets away, there would be no harmful consequences for retirees. Similarly, if the trust funds themselves were simply abolished, real economic activity would be unaffected. The government would not be relieved of any of its existing obligations or commitments. Or, as the late economist Robert Eisner suggested — with the stroke of a pen, we could double or even triple the number of IOUs the trust fund holds. Eisner’s idea would allow us to dispense with artificial crises (“trust fund running out of money!!”) and address the real problem: How is the Treasury going to pay the government’s bills?