From a great report on the U.S. national debt from Deloitte Touche Tohmatsu
Measuring America’s debt on an accrual, rather than cash basis, grows the current shortfall from $15.7 trillion to over $50 trillion. America’s debt is traditionally measured on a cash basis, which values the current debt at $15.7 trillion. However, the government regularly releases a report called the Financial Report of the United States Government in which it gives an estimate of the U.S. budget picture on an accrual basis for individual programs.
The inclusion of all of America’s long term unfunded liabilities into a single measure paints a far more difficult future picture for the U.S. over the longer term in which debt totals over $50 trillion dollars.
As with most cost estimates, the primary culprit in these estimates is Medicare, which further highlights the criticality of addressing this mandatory spending program. However, the sheer magnitude of these estimates shows that many deficit reduction initiatives simply fail to move the needle when compared with the stark shortfalls outlined by both the cash and accrual methods of accounting.