University of California San Diego economist James Hamilton recently published a paper in which he added up all the off-balance sheet liabilities, or rather, the hidden debt obligations that the U.S. federal government isn’t acknowledging that it has on its books. In totaling up the numbers, Hamilton finds that the actual size of the U.S. national debt actually exceeds $70 trillion, which through the end of the U.S. federal government’s 2012 fiscal year, is over $58 trillion more than the “official” total of the publicly-held portion of the national debt of $11.3 trillion.

We’ve excerpted Table 1 from the paper below, which shows how each off-balance sheet line item has changed in two year intervals from 2006 through 2012, which Hamilton presented on his blog:

A free version of the paper is available here, and Hamilton has also discussed his findings further at his blog as well. He emphasizes his bottom line:

Off-balance-sheet obligations of the U.S. government are quite substantial– 6 times the size of Treasury debt held by the public. But that does not mean that the real debt of the U.S. government is $70 trillion. Off-balance sheet commitments are of a fundamentally different character than those officially on the balance sheet.

Even so, off-balance-sheet commitments can be quite important. Here’s what I think is the correct conclusion to take away from these numbers:

…the budget impact associated with an aging population and other challenges could turn out to have much more significant fiscal consequences than even the mountain of on-balance-sheet debt already accumulated.

It would appear that the U.S. has much more to be concerned about in considering its obligations than many would have ever thought possible.

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