Mayor Mamdani defended his administration’s rollout of a property tax surcharge on second homes Wednesday amid criticism that the 17,000 New York City homeowners notified they may be subject to the pied-à-terre surcharge include some who live full-time in the city.

Some city residents told other outlets they’d received letters saying they may have to pay thousands more in property taxes despite being full-time New Yorkers. A Department of Finance spokesperson acknowledged that the 17,000 number could notch lower as some people verify they do, in fact, primarily live in New York City.

Mamdani said Wednesday the city is working to ensure that only those whose legal residence is outside of the Big Apple are taxed.

“The reason that we wanted to conduct outreach months in advance of when the tax would be levied would be to ensure that that exact premise would be fulfilled,” Mamdani said at a press conference Wednesday morning.

Gov. Hochul, who passed the pied-à-terre as part of the state budget, had previously said the surcharge was expected to impact 13,000 units in the five boroughs. The tax, which is estimated to rake in $500 million per year, was a middle ground between Mamdani’s push for raising taxes on the rich and Hochul’s hesitance to place more taxes on New Yorkers.

The tax will affect condominium and co-ops valued at more than $1 million, and 1, 2 and 3 family homes with a value of more than $5 million.

The bills are scheduled to be issued in November, with payment deadlines in January. If they miss the August deadline, homeowners have until March to appeal with the Tax Commission.

The finance department added 13 new positions in this year’s budget specifically to handle the tight turnaround of enacting the surcharge.

The issue of how the surcharge applies to co-ops has generated confusion. At Wednesday’s press availability, Finance Commissioner Richard Lee said that the agency is reaching out to co-op owners who received the letters in order to help them through the process, given that the co-op ownership structure could make administering the tax more complicated.

“It is a little bit of a new territory for us because of the way the surcharge is designed,” Lee admitted, adding that New Yorkers can get in touch with his department online or over the phone if they have any questions or concerns.

This also comes after the DOF released a list of property tax rolls with over 900,000 listings including property owners and market values, and its publication quickly drew backlash.

“This roll includes, but is not limited to, those properties that may be subject to the surcharge,” the list, posted online, read — generating confusion about whether the second home tax would be incorrectly applied more broadly.

“The tax property roll that was posted last week is a reflection of all properties across New York City, not a reflection of those, specifically, that the pied-à-terre tax will be levied upon,” Mamdani said Wednesday.