NYC Building Class Codes: What They Mean

A NYC building class code is a two-character label the Department of Finance (DOF) gives every property to describe how it is used: the letter is the broad type and the number adds detail, so C4 is a walk-up "old law tenement" and D4 is an elevator co-op. The code shapes the tax class a property lands in and gives you a quick clue about rent stabilization and financing, but it describes use for tax purposes, not what the building is legally allowed to be.

How the code is built

DOF's glossary for its property sales files explains it this way: the first position is a letter for a general class of property ("A" for one-family homes, "O" for office buildings, "R" for condominiums), and the second position, a number, adds more specific information about the use or construction style. DOF also says its building class is interchangeable with the term "building code" used by the Department of Buildings.

Roofy shows the plain-English family and the code on every building page, for example "Walk-up apartment building (C1)." The tables below decode the second character too.

Homes: A (one-family) and B (two-family)

A5 (attached or semi-detached) and A1 (two-story detached) are the most common one-family codes, and B1 and B2 the most common two-family codes. One- and two-family homes generally fall in tax class 1, which DOF assesses at 6% of market value rather than the 45% used for other classes.

Walk-ups: C codes

Elevator buildings: D codes

D4 (elevator co-ops) holds more apartments than any other single code in the city, followed by D1. The "fireproof" and "semi-fireproof" labels are DOF's construction categories; they are not a fire-safety rating and say nothing about a building's current violations.

Condos: R codes

Each condo unit is its own tax lot with its own R code, such as R4 for a residential unit in an elevator building. When City Planning rolls the units up into one record per building for PLUTO, it uses the unit code if every unit shares it; otherwise it assigns a mixed code it created, such as RM for a mix of residential and commercial units. That is why RM covers 286,488 apartments in PLUTO while R4 covers far fewer.

Mixed-use houses: S codes

Every other letter

A few codes in the live data, such as CB, CC, DB and DC, do not appear in the published appendix. They cover only a handful of lots; if you see one, treat the letter as the guide (C walk-up, D elevator) and check DOF's record for the property.

Why the code matters

Property taxes

DOF puts every property in one of four tax classes based on use. Its sales glossary describes class 1 as most residential property of up to three units (including small stores or offices with one or two apartments) and most condos of no more than three stories; class 2 as all other primarily residential property, including co-ops and condos; class 3 as utility equipment; and class 4 as everything else, such as offices, factories and garages. So A, B, C0, S1 and S2 codes usually sit in class 1, while larger C, D and R codes are usually class 2. DOF assesses class 1 at 6% of market value and classes 2, 3 and 4 at 45%. See NYC property tax classes.

Rent stabilization clues

The City says rent-stabilized apartments are most often in buildings with six or more units built before 1974. C1 and C7 are defined as over six families, and most C4 and D-coded lots in PLUTO also have six or more units, so an older building with one of these codes is worth checking. The code alone proves nothing: many buildings that fit the profile were deregulated or never covered, and HCR says rent stabilization also covers buildings that receive J-51, 421-a and 421-g tax benefits, whatever their age. Use the rent-stabilized checker and then request the apartment's rent history.

Financing and buying

C6, D4, and the loft conversions C8 and D0 mark co-ops, where you buy shares and finance with a share loan rather than a mortgage, and a board must approve you. R codes mark condos, which are bought as real property. See co-op vs condo and co-op share loans vs mortgages.

Where to look up a property's code

• On Roofy: search the address on the building lookup; the code appears under Building details.
• In PLUTO on NYC Open Data, field bldgclass. See PLUTO fields explained.
• In DOF's rolling sales files, which show the class both now and at the time of sale. Browse sales on Roofy's sales page.

If a code looks wrong, for example a two-family house listed as one-family, the tax record may be out of date. Renters should rely on the certificate of occupancy and HPD registration for the unit count.