The monthly budget deficit climbed to $85.97 billion in December from $78.13 billion in the same month a year earlier, partly because some payments normally made in January were shifted to December, the Treasury Department said on Thursday.
But for the first three months of fiscal 2012, which began on October 1, the cumulative deficit was down to $321.74 billion from $368.96 billion in the first three months of fiscal 2011.
Outlays in December rose to $325.93 billion from $315.01 billion in December 2010. One cause for the higher spending in December was about $4 billion in military retirement pay that was sent early because January 1 fell on a Sunday.
Government receipts, mainly from taxes, rose modestly to $239.96 billion in December 2011 from $236.88 billion in December 2010.
Under the government's accounting system, last October was the opening month of fiscal 2012. The fiscal 2011 budget deficit totaled $1.296 trillion.
The nonpartisan Congressional Budget Office last year projected a $973 billion budget deficit for all of fiscal 2012 but is due to issue updated figures later this month.
Congress has been attempting to find ways to shrink huge deficits but with scant success amid a bitterly partisan atmosphere on Capitol Hill.
Debate over another extension of the payroll tax cut is expected to resume when Congress reconvenes later this month. Many Republican lawmakers have said they oppose extending a reduction because of its fiscal cost and the effect on the Social Security retirement program it funds.