Zohran Mamdani used a Tax Day address from City Hall on Friday to put a specific number, a specific apartment and a specific name on his long-promised pied-à-terre tax — Ken Griffin's $238 million penthouse at 220 Central Park South, the most expensive home ever sold in the United States. The Citadel founder, Mamdani said, was "the cleanest possible illustration" of the "fundamentally unfair system" the tax was designed to dismantle.

Under the mayor's proposal, second homes in New York City with a market value above $5 million would be taxed on a graduated annual surcharge running from 0.5 per cent to 4 per cent. The city comptroller, in an analysis released alongside the announcement, estimated the policy would apply to roughly 11,200 properties and raise approximately $500 million in its first year of full implementation.

The tax requires Albany approval. Governor Kathy Hochul, who has spent much of 2026 distancing herself from the mayor's fiscal agenda, said on Monday she had "not been formally consulted" on the proposal but would "review any legislation submitted in good faith". Senate Majority Leader Andrea Stewart-Cousins has previously expressed support for a narrower version of the idea.

Griffin, who has not lived full-time in New York since relocating Citadel's headquarters to Miami in 2022, declined to comment through a Citadel spokesperson. He has previously called the New York tax environment "punitive" and has donated heavily to gubernatorial campaigns in Florida and Illinois. His 220 CPS penthouse, purchased in 2019 from developer Vornado for $238 million, remains the highest-priced US residential transaction on record.

Mamdani's broader budget compact also includes a separate $12 million expansion of peer-led substance-use recovery services, announced Monday morning, which will create roughly 500 new peer-specialist positions over four years. The administration says the funding draws on city, state and federal sources.

The Real Estate Board of New York has lobbied against pied-à-terre proposals in every Albany session since 2014, arguing the resulting price discount on luxury units would drag the broader market. REBNY president James Whelan, in a Monday statement, called the Mamdani plan "a familiar bad idea wrapped in a new political brand".

Mamdani, who took office on January 1 with a 49 per cent approval rating, has spent the first four months of his term consolidating an unusual alliance of progressive activists and centrist budget hawks. Friday's announcement appeared aimed at both — radical in framing, technocratic in detail.