What happens if you ignore the non-primary residence notice?

The notice asks you to tell the Department of Finance whether a qualifying person uses the property as a primary residence. Say nothing by the deadline, extended to September 18, 2026 for everyone who received a notice, and DOF works from the records it already has, which are the records that produced the notice in the first place.

The surcharge lands on the January 1, 2027 bill

The first surcharge is billed on January 1, 2027, with the second semi-annual property tax installment, and semi-annually after that. There is no separate invoice to set aside; it arrives inside the property tax bill. Existing abatements, credits and exemptions do not offset it, so whatever already reduces your bill keeps doing exactly what it did and the surcharge sits on top.

Unpaid means a lien

An unpaid surcharge becomes a lien. On a cooperative that lien attaches to the entire building, because the surcharge on a covered unit is assessed against the cooperative corporation rather than the shareholder. That is why one non-paying shareholder becomes every shareholder's problem, and why boards are moving on this early.

The window on the residence question closes

Once an initial determination is made, the appeal is filed in writing through the DOF electronic portal no later than 30 days after the date that determination is transmitted, or, if none is transmitted, 30 days after the surcharge appears on the assessment roll. The rule provides no extension and no hardship waiver. When do those 30 days matter? Once they run out, the year's non-primary determination stands as far as DOF is concerned. The procedure itself, filing to determination, is set out on how the appeal at the Department of Finance works.

The value challenge is on its own calendar

One route survives independently. A challenge to the property's value goes to the New York City Tax Commission on Form TC107, due March 1, 2027 for Class 2 and March 15, 2027 for Class 1, or 30 days after DOF's final determination, whichever is later. Read wrong value before you use it, because choosing the Tax Commission route replaces the direct exemption application to DOF.

Doing nothing is a decision. If a qualifying person really does live there, it is an expensive one, and the fix is documents rather than argument: what DOF accepts, and the order to put it in, is assembling the file. The filing walkthrough is how to respond.