The department said the surplus in June helped reduce the budget deficit for the first nine months of fiscal year 2013 fiscal year to $510 billion -- down 44 percent from the same period in 2012 -- MarketWatch reported.
Reduced spending contributed to the monthly surplus, but the Treasury Department said the deficit reduction was primarily due to higher tax receipts from individuals and corporations.
Total receipts are up 14 percent year-to-date because of higher payroll taxes and higher tax rates for wealthy Americans that took effect, MarketWatch said. Spending was down 5 percent during the October-through-June period.
The federal government posted a monthly budget surplus of $113 billion in April.
The Obama administration and the Congressional Budget Office have projected the annual deficit for the current fiscal year will be below $1 trillion for the first time since 2008.
The White House said this week it anticipated a full-year deficit of $759 billion, 4.7 percent of gross domestic product.
The CBO said in May the annual deficit would fall to $642 billion, or 4 percent of GDP.