There are plenty of ways to tally up the US government’s federal debt. The total Treasury debt outstanding was about $16.74 trillion at the end of July. But the US owes about $4.84 trillion to itself, mostly in the form of debt that is issued to entities such as the Social Security trust fund. So many analysts tend to focus on the $11.91 trillion in debt that is publicly available to be traded.

There are plenty of ways to tally up the US government’s federal debt. The total Treasury debt outstanding was about $16.74 trillion at the end of July. But the US owes about $4.84 trillion to itself, mostly in the form of debt that is issued to entities such as the Social Security trust fund. So many analysts tend to focus on the $11.91 trillion in debt that is publicly available to be traded.
As we noted earlier this week, the recent revision of US GDP—which boosted the size of the world’s largest economy by about $590 billion in 2012—instantly shrank the debt-to-GDP ratio to less than 70%. That debt load looks downright manageable if you compare it to burdens on the books of troubled European countries, for example.
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But that’s just the stuff that’s “on the books.” Like many countries, the US has large stockpile of potential and actual liabilities that don’t show up on as actual debt outstanding. In fact, a new working paper by University of California-San Diego economics professor James Hamilton estimates that the US was on the hook for more than $70 trillion in off-balance sheet liabilities at the end of 2012. Yes, trillion.

How is that possible? Well, here’s Hamilton’s tally.
Housing related commitments
Student and other loan guarantees
FDIC
The Federal Reserve
Social Security
Medicare
Other government trust funds
Total
Does this staggering amount of debt spell imminent doom for the country? Not really. As we’ve said before, it’s highly unlikely that the US would have to come up with all of this money at any one time. Nor are all of these costs absolutely going to happen as actuaries predict. For example, if the US really doesn’t have the money to pay for all of the Social Security benefits retirees are entitled to in a few decades, those benefits could be trimmed then, or other alterations could be made to the program—such as pushing the retirement age back, which would cut the costs of the program.
On the other hand, it is important to remain cognizant of the fact that the US government—and most other governments of large advanced economies—are usually on the hook to pay for many things that don’t show up on the annual budget. Of hazy liabilities, Hamilton writes: “Acknowledging their size is a necessary first step for making wise policy decisions.”