April tax collections beat the Healey administration’s expectation by more than $1 billion, driven by revenue from the surtax on annual income above $1 million and capital gains taxes, the Department of Revenue said Monday.

Last month’s $6.838 billion in tax revenue was $511 million or 8.1% greater than what was collected in April 2024, and $1.116 billion or 19.5% more than the administration’s monthly benchmark.

With just two months left in fiscal 2025, DOR said tax receipts total approximately $36.517 billion — $2.658 billion or 7.8% more than actual collections by the same point in fiscal 2024 and $1.9 billion or 5.5% above the year-to-date benchmark, DOR said.

DOR and Administration and Finance Secretary Matthew Gorzkowicz both attributed much of the monthly and year-to-date overage to surtax and capital gains collections, revenues that have restrictions on their use and are not available to support some general budgeted spending.

“The revenue overperformance in April is largely driven by Fair Share surtax and capital gains collections — categories that do not alleviate persistent pressures on the overall state budget tied to the escalating costs of providing state services,” Gorzkowicz said.

Almost all of April’s over-benchmark performance came in the non-withheld income category, which officials have said is a signal that the revenue stems from the income surtax on high earners or capital gains taxes. Income tax revenue beat expectations by $1.23 billion or 30.7%, $1.21 billion of which came in the non-withheld income category that captures revenues from capital gains taxes and the income surtax.

An administration official explained that the revenue benchmarks assume $1.3 billion in surtax revenue this year, consistent with the consensus revenue agreement with the Legislature. But the Healey administration thinks actual surtax revenues will be about the same as in fiscal year 2024, when the state collected $2.46 billion from the surtax.

That means there is nearly $1.2 billion in revenue that the administration thinks will come in, but which is not assumed in its formal revenue expectations.

Similar to last year, the dynamic means Massachusetts can likely sock away $1 billion or more in surtax revenue to be spent later for education and transportation while still having to closely monitor tax collections in May and June to ensure a balanced budget when the fiscal year ends.

For May, the administration’s benchmark is set at $2.49 billion, which would be $44 million more than was collected in May 2024. May revenues are due from DOR by Wednesday, June 4.