The latest figures, disclosed in court filings this week and addressed by Mamdani at a Bronx press conference Wednesday, offer the clearest picture yet of how the Department of Finance (DOF) is narrowing the pool of properties that could ultimately face the new pied-à-terre tax.

DOF initially identified about 26,000 properties that met the tax’s applicable value thresholds. Before sending notices, the agency used property-tax exemptions, co-op and condo abatement records and available state income-tax information to determine that more than 8,000 of those properties appeared to be primary residences.

That left about 17,000 properties whose owners received notices beginning in July saying their homes may be subject to the surcharge because the city could not verify that they were qualifying primary residences.

Since then, that pool has continued to shrink. As of Aug. 24, a rough calculation using the filing’s figures leaves a number in the neighborhood of 13,000 initial determinations not yet cleared.

But that is not the same as saying 13,000 properties will ultimately owe the tax: thousands of submissions remain under review, and other owners still have time to provide information showing their property should not be subject to the surcharge.

As of Aug. 24, DOF had received 5,544 submissions from property owners seeking to demonstrate that their homes are primary residences and had approved 2,892 of them, according to an affirmation filed by DOF General Counsel Michael Smilowitz in the ongoing Staten Island lawsuit over the rollout. The remaining submissions were still under review.

Separately, the state provided DOF with preliminary 2025 income-tax information on Aug. 12, several months earlier than the agency would normally begin receiving it. DOF then compared that data with the properties that had received initial notices.

The agency said it revised its initial determination for some 630 property owners whose 2025 tax returns identified the property as their permanent home. Another approximately 580 were cleared based on a combination of their 2025 tax-extension information and 2024 returns.

Those approximately 1,200 revised determinations are separate from the nearly 2,900 primary-residence submissions already approved, according to the filing.

Mamdani insists it won’t impact revenue estimate

Asked Wednesday whether the changing number of potentially taxable properties threatened the city’s revenue estimate, Mamdani said it did not.

“We continue to be confident in that assessment of what the annual revenue will look like,” the mayor said.

The $500 million figure has been attached to the tax since before its final form was enacted. Gov. Kathy Hochul’s administration initially estimated in April that about 13,000 NYC properties were “basically” second homes as officials worked on a proposal designed to generate at least $500 million annually.

The city comptroller’s office also analyzed an earlier version of the proposal in April and found that a little more than 11,200 properties could generate almost exactly $500 million under one set of rates and assumptions before accounting for rentals and changes in owners’ behavior. But that analysis predated the final law and warned that collections could fall substantially depending on exemptions and how property owners responded to the tax.

What remains unclear is how many properties the Mamdani administration now expects will ultimately pay the surcharge under the enacted law and what current assumptions underpin its $500 million forecast. DOF did not immediately provide an updated estimate of how many properties it expects will ultimately be subject to the surcharge; amNewYork is awaiting those figures.

DOF’s latest court filing does not provide a projected final taxpayer count or a revenue model. Instead, it lays out how the agency is continuing to sort through the remaining properties.

About 4,400 owners are set to receive updated letters saying DOF’s review of their 2025 tax information and other records still does not establish that the property is a primary residence. Owners of another 6,400 properties held through entities or trusts will receive similar letters explaining what additional information the agency needs. DOF said it is working to send about 10,800 letters before Aug. 31.

Those properties have not been determined to owe the tax. Rather, DOF says it still lacks enough information to establish that they qualify as primary residences.

The agency has also extended the deadline again for owners who received an initial determination notice to submit primary-residence documentation to Oct. 6. Mamdani stressed Wednesday that property owners who do not resolve their status by the new deadline can still appeal an assessment to the Tax Commission into early next year.

The new figures emerged as part of the city’s response to a lawsuit brought by homeowners challenging the way the Mamdani administration rolled out the surcharge, rather than the legality of the tax itself.

The city is seeking to dismiss the case and argues that the homeowners lack standing, noting that every plaintiff who received an initial determination notice has since been told their property is not subject to the surcharge. The administration is also defending its publication of a much broader supplemental property roll, saying state law required DOF to publish information on covered properties even though the vast majority would never owe the tax.

Staten Island Supreme Court Justice Wayne Ozzi temporarily blocked parts of the rollout earlier this month, but that order remains stayed as the city challenges it and continues implementing the surcharge. The case is scheduled to return to court Aug. 31.