Massachusetts’ preliminary revenue collections for April totaled $2.5 billion, a 43.4 percent increase from the same period a year ago, according to the Department of Revenue (DOR).

Total tax collections were $587 million above the monthly benchmark based on the Jan. 18 fiscal year 2011 revenue estimate of $19.78 billion, according to a statement.

"The strong April collection was largely due to payments with income tax returns and extensions generated by larger than expected investment-related income which produced higher than forecast revenues from taxes due on interest and dividends and capital gains," said Revenue Commissioner Navjeet K. Bal. "Monthly withholding also registered above benchmark, which is a sign of continuing economic recovery."

The DOR expected the April collection to be larger than that of a year ago when many taxpayers took advantage of a filing deadline extension due to flooding and waited until May 11 to file, according to a statement. But the monthly collection of $587 million above benchmark stems from other factors as well.

"Capital gains collections are volatile, as we have seen most recently in fiscal year 2009 when capital gains dropped $1.7 billion due to the economic decline of 2008," Bal said. "For that reason, we should not assume continued revenue growth at this rate. We will examine tax returns filed this fall by those taxpayers who now have extensions to further probe the reasons for this dramatic increase, but it is clear that much of it stems from taxpayers who decided to cash in investments in calendar year 2010, and who are now paying taxes on those realized gains."