According to the US Treasury Department, the US budget deficit rose by 68.4% to $88.4 billion in May from $52.507 billion a year earlier.
Receipts from individual and corporate taxes rose by 7% to $240.418 billion.
Meanwhile, spending grew by 18.7% to $328.844 billion amid a boost in defense costs and a rise in Medicaid healthcare costs for the poor.
The US budget deficit widened by 6.8% to $432.853 billion for the fiscal year 2017, which lasts from October 1, 2016, compared with $405.413 billion a year before.
Since the beginning of the current fiscal year, budget receipts have increased by 1.4%, to $2.169 trillion, while expenses have risen by 2.3%, to $2.602 trillion.
In late January, the Congressional Budget Office (CBO) projected that the deficit for the fiscal year 2017 will decline to $559 billion or 2.9% of GDP. That compares with its previous estimate of $594 billion.
According to the US Treasury, the deficit for the full budget year 2016, which ended on September 30, increased to $585.646 billion, for the first time in five years. Thus, it grew to 3.2% of GDP compared to 2.4% of GDP a year earlier. It was the first time the deficit increased in relation to economic output since 2009.