With New Jersey tax collections growing at less than half the rate forecasted by Gov. Phil Murphy’s administration, a Wall Street ratings analyst says there’s reason to be worried the state budget may not take in enough cash for the rest of the fiscal year.

The $37.4 billion state budget, signed into law in July, assumes revenues will grow 7.5 percent over the previous fiscal year, a figure that takes into account new personal and corporate income tax rate hikes. But the state Treasury Department reported earlier this month that growth has slowed to 3 percent.

The gap between the state’s 3 percent growth from July through January and its 7.5 percent target works out to about $740 million, according to S&P Global Ratings, a Wall Street rating agency.

Without a $282 million bump from a successful winter tax amnesty program, growth would have registered at just 1.3 percent.

S&P said there is worry New Jersey could end the fiscal year in the red.

The Treasury Department said the shortfall could be the result of taxpayers adapting to a new federal income tax landscape.

High earners who customarily made their estimated tax payments in December to take advantage of the state and local tax deduction may be waiting until closer to the April filing deadline now that the deduction is capped at $10,000, the department said in its monthly report.

Treasury is optimistic the state will get a boost in April tax collections that makes up for the December and January slump.

S&P Global Ratings said in its analysis Monday that taxpayer behavior could explain away December’s lackluster numbers, or maybe declines in the stock market wiped away capital gains. But continued revenue troubles in January “might be harder to explain.”

Sales tax collections aren’t hitting their target either, and S&P’s analyst, David Hitchcock, didn’t express much confidence the state could turn things around before the June 30 end of the fiscal year.

“While a major portion of income tax is received in April and potentially reduced refunds could make up some lost ground, the extended revenue shortfalls in the first half of the year will make catching up by the end of the year more difficult, even if currently slow revenue trends reverse," Hitchcock wrote.

While officials in New York blamed their similar revenue troubles on wealthy residents fleeing high-tax states, S&P Global Ratings said research is mixed and “regardless of whether significant tax migration from New Jersey exists, we believe the long-term revenue and budget picture could become much clearer by July after New Jersey adopts its fiscal 2020 budget and tabulates final figures from this spring’s April income tax period.”

Treasury spokeswoman Jennifer Sciortino said the state is “taking a measured approach and intend to wait until after the April income tax filing deadline before we make any definitive conclusions about the year’s total revenues."

Samantha Marcus may be reached at smarcus@njadvancemedia.com. Follow her on Twitter @samanthamarcus. Find NJ.com Politics on Facebook.