421-a expiration calculator

What happens to the taxes when a 421-a abatement expires?

Many newer NYC buildings got a temporary tax discount from the city — called a 421-a or J-51 abatement — that lasts 10 to 25 years and then runs out. When it does, tax bills can jump 3–5×, so a monthly payment that looks affordable today might not stay that way. Type an address to see its tax breaks on record, roughly when they end, and what the bill could look like afterward — straight from the city’s own records.

Estimates use the current exempt value and FY2026 class rates; real 421-a benefits phase out gradually (typically 20% steps), so the full amount arrives over the final years rather than at once. Condo units are assessed individually — building-level lots show building-wide figures.

Buying in a 421-a building?

Ask for the abatement’s start date and schedule, not just “has 421-a.” A monthly payment that works today can rise by hundreds or thousands when the benefit ends — run the post-abatement tax through the mortgage calculator before you commit.

Building or buying new? Projects that started construction after June 15, 2022 use 421-a’s successor instead — see the 485-x calculator for its 10–40-year schedules.