The May deficit figure was smaller than the Congressional Budget Office's estimate of $71 billion, The Wall Street Journal reported.
The department's monthly budget statement reported the May deficit was up 58 percent from a $42.91 billion shortfall a year earlier.
Outlays were $231.94 billion in May, down 2 percent from a year earlier, the CBO report said. Government receipts were $164.24 billion, down 15 percent from a year earlier.
The Treasury estimated the government ran a budget deficit for the first eight months of fiscal 2007 of $148.45 billion, down 35 percent from the fiscal year-to-date deficit a year earlier.
For the first eight months of fiscal 2007 -- October to May -- receipts totaled $1.669 trillion, up 8 percent from the same period in fiscal 2006. Outlays so far totaled $1.817 trillion, up 3 percent from the same reporting period a year ago.