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NYC Property Intelligence

NYC Building Classes — Complete Guide

Every NYC tax lot has a Department of Finance class code that determines which laws, deadlines, and compliance obligations apply. Here are the 8 most common — explained in depth.

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8 classes covered · NYC DOF · PLUTO-sourced · official sub-codes

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What are NYC building classes?

NYC building classes are single-letter codes (A through Z) assigned by the NYC Department of Finance to every tax lot to describe its primary use and structure. The main residential classes are A (1-family), B (2-family), C (walk-up multi-family), D (elevator multi-family), R (condominium), and S (mixed-use residential). Commercial classes include O (office), K (retail), and L (loft). Each class carries sub-codes providing more specific characterization.

Residential classes

Class A — One-Family Dwellings → ~295,000 properties citywide

Single-family detached, attached, or semi-detached homes

Class B — Two-Family Dwellings → ~225,000 properties citywide

Two-family homes including traditional Brooklyn/Queens two-family layouts

Class C — Walk-Up Apartment Buildings → ~110,000 buildings (~1.5M+ units)

Multi-family buildings without elevators

Class D — Elevator Apartment Buildings → ~8,500 buildings (~650,000+ units)

Multi-family buildings with elevators — mid-rise and high-rise residential

Class R — Condominiums → ~275,000 condo units citywide

Individual condo units (residential)

Mixed-use classes

Residential buildings with ground-floor or mixed commercial space

Commercial classes

Class O — Office Buildings → ~4,200 office buildings citywide

Office buildings — small neighborhood buildings to Class A towers

Class K — Store Buildings → ~11,000 store buildings citywide

Retail store buildings — primarily commercial, little or no residential

Frequently Asked Questions

What is an NYC building class?

An NYC building class is a letter-based classification assigned by the NYC Department of Finance (DOF) to every tax lot. Classes range from A (single-family) to Z (miscellaneous). The letter indicates the primary use and structure type (A, B, C, D = residential; O = office; K = retail; S = mixed-use; R = condominium). Each class has an associated sub-code (like A1, C4, D3) providing more specific characterization.

Where does the building class appear in NYC records?

Building class is a field in the PLUTO dataset (Primary Land Use Tax Lot Output) maintained by NYC Department of City Planning, which draws from the DOF assessment roll. You can see your building's class in any RegWatch property report, on the DCP's ZoLa portal, or in the raw PLUTO data on NYC Open Data.

Why does building class matter for compliance?

Building class drives which NYC regulations apply to your property. Class A (1-family) has minimal HPD obligations. Class B (2-family) is exempt from Multiple Dwelling Law. Class C (walk-up) requires annual HPD registration. Class D (elevator 6+ stories) adds FISP façade inspections, annual elevator inspections, and likely LL97 carbon compliance. Knowing your class is the first step to understanding your compliance calendar.

Can a building have multiple classes?

A building typically has one primary DOF class per BBL. However, condominiums are interesting — each condo unit has its own BBL and gets a Class R designation, while the underlying building retains its original class (often D for elevator buildings). Co-ops by contrast remain classified as whole-building structures (C5, C8, D4, D7, etc.).

How do I change my building's class?

You don't directly — building class is determined by DOF based on the property's actual use and configuration at assessment time. To effect a class change, you typically need to file with DOB for a Certificate of Occupancy change (e.g., 1-family to 2-family, commercial to residential), which then flows to DOF on the next assessment cycle. Contact DOF directly if you believe your current class is incorrect.

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NYC Building Classes A–K Explained | RegWatch