New York’s newly approved pied-à-terre tax could force entire co-op buildings to shoulder major financial burdens if wealthy second-home owners refuse to pay, according to real estate professionals and co-op advocates who say the law does not properly account for how cooperative ownership works.

“It’s not the shareholder that suffers the consequences, it’s the entire building that suffers the consequences,” Jason Haber, co-founder of the American Real Estate Association and a Compass broker, told The NY Post.

The tax, pushed by Gov. Kathy Hochul and supported by Mayor Zohran Mamdani, was included in the state budget and signed into law last month.

The measure targets luxury residences that are not owners’ primary homes and is projected to bring in hundreds of millions of dollars each year from affluent second-home owners.

However, real estate experts warn that collecting the surcharge could create significant complications for co-op boards, especially in smaller buildings.

Unlike condominiums, where each apartment has its own separate tax lot, co-ops are treated as a single property for tax purposes.

The building pays the property taxes as one entity, with costs then passed on to shareholders through monthly maintenance fees.

“As regards to the pied-à-terre tax, the legislation requires the co-op to pay the surcharge in the same way that they pay their real estate taxes, and the co-op must then charge the impacted shareholder back and hope to collect the surcharge from them,” Rebecca Poole, director of membership and communication for the Council of New York Cooperatives and Condominiums, told The Post.

That system could force co-op boards to cover large payments upfront while trying to recover the money from owners who may not live in the building.

“It’s possible that co-ops could be out the funds while waiting for the shareholder who is subject to the surcharge to pay the charge back,” Poole said.

The issue could be especially difficult for smaller buildings where one expensive apartment could generate a major tax obligation.

“For example, if you have a five-unit co-op and the pied-à-terre tax applies to the largest unit — which may be comprised of a couple of combined units — the other four shareholders might be forced to quickly come up with a large sum of money that they don’t have to pay, the surcharge, while they try to collect the funds from an out-of-town pied-à-terre owner,” Poole said.

Haber said enforcement could create additional complications because co-ops do not have separate tax parcels for individual apartments.

“You cannot put a tax lien on an individual unit in a cooperative because there is no tax lot for that unit,” Haber said.

“Instead, what do you do? You put a lien on the entire building.”

Haber said a conflict involving one shareholder could potentially impact everyone living in the building.

“If someone’s trying to sell their apartment and the buyer is getting financing, that buyer may not be able to get financing because of the tax lien,” he said.

“It creates a cloud on the building.”

He argued that lawmakers did not fully consider the structure of co-op ownership when creating the policy.

“There’s only one tax lot for the entire building, so how do you assess a tax on an individual shareholder? This is the problem,” he said.

Poole said many co-op boards are still trying to figure out whether the new surcharge applies to their properties and which shareholders could be affected.

“The two problems we potentially see happening are lack of clarity among co-ops in general as to whether or not this will apply to them, because in the press it’s been about the $5 million figure and the market value doesn’t line up with that exactly,” she said.

She said boards should begin reviewing their buildings now to prepare for possible impacts.

“The first step we’re encouraging is for co-op and condo boards to look and see if this will apply to any of their apartments and then start to prepare,” Poole said.

Haber said some boards are already considering limiting future pied-à-terre ownership to avoid possible financial exposure.

“The whole building is impacted if one shareholder doesn’t pay the tax,” he said.

A spokesperson for Gov. Hochul told The Post that “the city will identify who is covered by the law, communicate that to the boards, who are then required to pass that information on to the owner.”

“The boards don’t have to tally their own bill and aren’t penalized for anything to do with reporting info,” Hochul’s office told The Post.

“Co-ops are already responsible for collecting property taxes, so it makes sense that they would also collect a surcharge.”

The governor’s office also said the law “includes tools for the city to directly enforce against the unit owner, in addition to the co-op’s own right to collect from the shareholder.”

“In a co-op setting the building’s property taxes already are determined at the building level and then apportioned based on stockholders’ ownership shares,” the governor’s office told The Post.

“That is sensible in the context of a coop, where a unit owner actually has a percentage of shares in the corporation that owns the underlying property.”

When asked about whether co-ops might ban pied-à-terre arrangements to avoid liability, the governor’s office said: “This tax applies to a narrow class of high value, secondary residence that by definition are not primary residences for New Yorkers.”

“Nothing in this policy would diminish housing options made available to New Yorkers.”