Massachusetts officials acknowledge a $311 million year-to-date revenue shortfall that could complicate efforts to finalize a budget for fiscal 2017.
The new spending plan is due later this month.
State revenue Commissioner Michael Heffernan late Friday said revenue collections for May were $50 million below benchmark for the month, the second straight monthly drop.
May is normally a small tax collection month, he said, with the filing season winding down and no quarterly estimated payments due for most corporate and business taxpayers or individuals.
"We continue to have confidence in the state's economy as overall sales tax and income withholding revenues remain healthy," Heffernan said in a statement.
The Senate late last month passed a $39.6 billion budget after adding $61.3 million on the floor, primarily to local education. The House in April approved a fractionally smaller $39.5 billion plan.
By state law, a panel of Senate and House negotiators will work out a final version, upon which both chambers will vote and send to Baker.
Massachusetts ranked next to last in fiscal health, only behind Connecticut, according to a report last week by George Mason University's Mercatus Center in Arlington, Va. Mercatus researchers culled data from fiscal 2014 comprehensive annual financial reports and rated the states using various solvency metrics including cash, budget and long-run.
Massachusetts only has between 0.39 and 1.12 times the cash needed to cover short-term liabilities, according to Mercatus.
Fitch Ratings and Standard & Poor's rate Massachusetts general obligation bonds AA-plus. Moody's Investors Service rates them Aa1.
Massachusetts intends to sell $500 million of Series D and Series E tax-exempt general obligation bonds competitively this week. Acacia Financial Group is the financial advisor.
State Treasury officials have scheduled an investor call for 1:30 p.m. Tuesday.