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.
Read MoreThe deficit is shrinking! Why is no one cheering?
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.