Gov. Maura Healey defended a $1 billion-a-year package of tax cuts signed into law last year after her administration said this week that Massachusetts is expected to collect $1 billion less in fiscal year 2024 revenues than originally anticipated.

Some critics of the tax law expressed skepticism toward Healey’s decision Monday to slash $375 million from the state budget to make up for the deficit while also calling tax reform enacted last year a boon to the “very rich.”

But Healey, a Democrat, said the tax package was “absolutely essential.”

“These were all efforts to make life more affordable for folks in the state,” Healey said at the State House Tuesday. “We accomplished that with the tax package, 70% of that tax package going to lower- and middle-income families across Massachusetts. That’s real savings. That’s really important, and it’s a delivery on a promise that we made.”

Reforms signed into law last fall lowered the tax on profits from short-term investments from 12% to 8.5%, a business-backed move that created a flurry of blowback from progressive groups that argued it gave a break to the wealthy.

Beacon Hill lawmakers and Healey also worked in boosts to the rental deduction cap, a tax credit for a dependent child, disabled adult, or senior, and the statewide cap for a housing production program. The law also excluded estates valued up to $2 million from the estate tax by allowing for a uniform credit of $99,600.

Massachusetts Teachers Association President Max Page and Vice President Deb McCarthy said they warned the cuts had “consequences” when discussions were first had about “providing tax cuts to the very rich.”

“We are seeing the fall out: cuts in funding — similar in size to the tax cuts given to the very wealthy — for education, transportation, childcare and housing, which will impact regular, working people,” Page and McCarthy said in a statement.

Progressive Massachusetts, a policy group, said 2023 was “not the time for permanent regressive tax cuts.”

“We remain disappointed that so many legislators chose not to listen,” the group said on social media in response to the financial headwinds.

Budget cuts announced Monday came as Administration and Finance Secretary Matthew Gerkowicz said Massachusetts is expected to see $1 billion less in tax revenues than budget writers first projected for fiscal year 2024.

Healey made $375 million in unilateral budget cuts — mostly affecting social programs throughout Massachusetts and MassHealth — and turned to $625 million in “non-tax revenues,” most of which comes from increased investment earnings, to make up the hole on the balance sheet.

No layoffs nor future cuts are expected but Gerkowicz told reporters officials expect 12 to 18 months “where we have to do some belt tightening.”

“But overall, we don’t see this as being in a recessionary environment, and we believe the economy will continue to grow in (fiscal year 2025),” he said.

Still, Page and McCarthy said the voters who approved a 4% surtax on incomes above $1 million — sometimes dubbed the Fair Share Amendment or Millionaires Tax — “are no doubt stunned by (Monday’s) announcement about state budget cuts.”

Healey likened the budget cuts to little more than when someone rebalances their own personal budget sheet, and called the $375 million slash to fiscal year 2024 “fiscally responsible and appropriate.”

“You’re probably going through this at home, too. It’s the end of the year, the start of the new year, we all take a look at our bank statement and we see how we did and where we’re spending money,” Healey said. “And as you know, this year, it turned out that we saw a little bit less in revenue than we’d seen in years past where we’ve seen really record revenues.”