What will the pied-à-terre tax cost?

The number that drives everything is the Department of Finance market value, not a sale price and not an appraisal an owner commissioned. Condominium and cooperative units are reached at $1 million of that value, one- to three-family homes at $5 million, and once a property crosses its threshold the rate applies to the entire value.

It is a cliff, not a bracket

Income tax works in brackets: cross a line and only the part above it is taxed at the higher rate. This does not work that way. The adopted rule says it directly, that if a property or cooperative dwelling unit's valuation exceeds the threshold, the entirety of the property's value is subject to the surcharge. A value landing a few thousand dollars over a line re-prices everything underneath it, which is why the exact figure DOF used matters more here than in almost any other property tax question.

The city's value is not your sale price

DOF values Class 2 property by an income method that runs well below open-market prices. The reported rule of thumb is that a $1 million DOF market value corresponds to roughly a $5 million apartment. Owners who read the threshold against their own purchase price usually conclude it cannot reach them, and are looking at the wrong number.

One notice, two numbers

From a single notice, with nothing identifying attached: a market value of $5,268,000 and an annual surcharge of $42,144.00. That pair is an illustration, not a rate schedule. Which ladder applies? That depends on the property's tax class, which is why the tool asks first.

How is the number computed? The methodology sets out the ladders and what the tool deliberately leaves out. Co-op values explains why a cooperative unit's figure looks nothing like the apartment it belongs to.