The Committee for a Responsible Federal Budget (CRFB) estimates lawmakers added $1,412,038,866,702 to the debt for the 2010 fiscal year, which ended Thursday.
Gross debt, which includes public debt and intergovernmental holdings, went from $11.9 trillion to $13.5 trillion during FY 2010, the group stated.
Debt increased even though Congress failed to send a single appropriations bill to President Obama's desk, the group noted.
"Congress has failed to pass even one of the 12 appropriation bills to FY2011 before the new year actually started," the group states.
Lawmakers are expected to return to Congress after the November elections, and Democratic leaders have said extending the Bush-era tax cuts for the middle class is their main priority. The CRFB states this will add at least $1.7 trillion to the debt and deficit.
Congress is also expected to pass legislation that would prevent the alternative minimum tax from being imposed on some middle-class taxpayers. Doing so will add more to deficit, because the budget scorecard now anticipates the government will take in revenue from this tax.
The committee criticized members of both parties for not doing enough to rein in the deficit, but expressed hope that things will change next year.
"No one has offered a plan for offsetting a partial extension [of the tax cuts] either, the cost of which would be even higher when factoring in AMT patches and interest payments," the group states. "Let's hope that FY2011 is a turnaround year."