Last month's surplus was slightly smaller than the $114 billion figure expected by analysts polled by Reuters.
Tax receipts have surged this year as the economy has improved. The Congressional Budget Office expects the deficit will shrink to $492 billion during the fiscal year, which began in October. In 2013, the government ran a $680 billion deficit.
So far this year, the government has run $306 billion into the red. That deficit is 37 percent smaller than it was in the same period of fiscal 2013.
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Last month's receipts were $8 billion higher than they were in April of last year. Outlays were also higher, though they have been on a downward trend in part because an improved labor market has led fewer people to draw on jobless benefits.
The expiration of benefits for many long-term unemployed workers in January has also reduced outlays.