The Financial Report of the United States, which applies corporate-style accrual accounting methods to Washington, showed the government's liabilities exceeded assets by $14.785 trillion, compared with a $13.473 trillion gap a year earlier. 

"This report provides another sobering picture of our long-term fiscal challenges," US Treasury Secretary Timothy Geithner said in a letter accompanying the report.  

"Restoring fiscal sustainability will require substantial additional changes, including tax reforms to increase revenue and changes to make our entitlement programs sustainable over time," Geithner said.

An earlier report estimated US government revenue in fiscal 2011 at 15.4 percent of gross domestic product, up slightly from 15.1 percent in fiscal 2010 but still one the lowest levels since the end of World War II.

That same report estimated government outlays in both fiscal 2010 and 2011 at 24.1 percent of GDP, which was one of the highest levels of the last six-and-a-half decades. 

Unlike the normal measurement of government intake of receipts against cash outlays, accrual accounting measures costs such as interest on the debt and federal benefits payable when they are incurred, not when funds are actually disbursed.

The report was instituted under former Treasury Secretary Paul O'Neill, the first Treasury secretary in the George W. Bush administration, to illustrate the mounting liabilities of government entitlement programs like Medicare, Medicaid and Social Security.

The government's net operating cost, or deficit, in the report dropped to $1.313 trillion for the year ended Sept. 30 from $2.080 trillion the prior year, reflecting increased tax and other revenues and a drop in expected future payments under government pension programs.