The socialists have been swooning ever since Mayor Zohran Mamdani announced he had managed to balance New York City’s $125 billion budget.

Sen. Bernie Sanders (I-Vt.) acclaimed the new mayor for confronting “a huge budget deficit” and bringing it “down to zero,” while still boosting spending.

“This Man is a LEGEND,” gushed Mamdani superfan Ryan Rozbiani on X.

“Something that nobody else could do,” marveled lefty influencer Suzie Rizzio.

Funny how these progressives don’t acknowledge how Mamdani is doing it: by burdening future taxpayers with pension costs he’s refusing to pay now. So much for being the party of the working man.

Mamdani has spent his career bemoaning “austerity,” a label reflexively applied to almost any effort to constrain the growth of government spending.

The mayor doesn’t want to be accused, by public employee unions or his fellow Democratic socialists, of practicing austerity — so instead he’s using a feature in the way New York City pays for pensions to make the next mayor do it instead.

New York City, like many public employers, for years promised bigger pensions than the funds set aside while employees were working would cover.

That became especially clear after the Great Recession: Retirees were living longer and investments weren’t generating the huge returns on which the pension systems depended.

Making things worse, Albany had retroactively sweetened pension benefits, creating new liabilities for taxpayers to fund after the fact.

So New York City kicked the can down the road, devising a plan to pay off this newfound pension debt, with interest, over 22 years — into the early 2030s.

Rather than cut costs to balance his budget, Mamdani got permission from Albany to shove those pension costs even further into the future.

Under the new legislation, the city pension systems (which also cover the New York City Transit Authority, Health+Hospitals and a few small agencies) would get $31 billion toward that old pension debt between this year and mid-2032, instead of the $48 billion they had expected.

But that money will have to be paid eventually — with even more interest.

Put simply, Mamdani is forcing taxpayers to spend a total of $7 billion on interest to avoid having to trim between $2 billion from the annual budget in this and most of his possible second term — and then to slam the mayor who takes office in 2033 with about $4 billion per year in completely avoidable costs. All to avoid the dreaded A-word.

Those out-year costs, and the pressure they’ll put on existing city programs, conveniently don’t show up in City Hall’s out-year projections.

The mayor should be confronting the city’s longstanding mismatch between revenue and expenses without resorting to gimmickry, especially absent an emergency or recession.

Doing the tougher things today, like consolidating half-empty schools, changing the way the city provides employee benefits or deploying more technology in city agencies, would both improve services and reduce costs in the long run.

But someone might call that “austerity.”

So let the next mayor worry about it.

This one’s devoted disciples sure won’t.

Ken Girardin is a fellow at the Manhattan Institute.