In addition to the national debt, the US government also owes another $7318.6 billion as of 9/30/2011. Most of this is accrued federal employee and military retirement benefits, but it also includes environmental liabilities, contingent liabilities to Fannie Mae, and Freddie Mac. These should also be included in the US debt.
The FRUSG claims that the Social Security trust fund amounts should not be included: "In addition to debt held by the public, the Government reports about $4.7 trillion of intragovernmental debt outstanding, which arises when one part of the Government borrows from another. It represents debt held by Government funds, including the Social Security and Medicare trust funds, which are typically required to invest any excess annual receipts in Federal debt securities. Because these amounts are both liabilities of the Treasury and assets of the Government trust funds, they are eliminated in the consolidation process for the Government-wide financial statements." This hurts my head to think about it. There is no doubt that at least $4.7 trillion is owed to trust fund recipients. Is there a bank account somewhere with $4.7 trillion in it? I think not, so don't exclude it.
So the actual federal debt as of 9/30/2011 is $22109 billion, of which $10127 is debt held by the public, $4663 is intragovernmental holdings, $5792 is "Federal Employee and Veterans Benefits Payable" (hereinafter "fed retirement benefits"), and $1527 is other liabilities.
Should interest be accrued on these other debts? Yes, and here's why. Maybe interest isn't formally due, but the costs to repay these debts will continue to rise. For example, cleaning up a hazardous waste site will be more expensive in the future. I am using 3% as a long-term interest rate, so there should be a line item for "Accrued interest on non-public debt" or something similar.
Should the debt be offset with federal assets? No, unless there is a serious plan to sell off national parks or aircraft carriers.
So the next time I do a projection, I will include these other liabilities on it.