- Glossary
- /Certificate of Occupancy (C of O)
NYC rental glossary
Certificate of Occupancy (C of O)
The DOB document stating a building’s legal use and how many units it may lawfully contain.
A Certificate of Occupancy is the Department of Buildings document that states what a building may lawfully be used for and how it may be configured — how many dwelling units, what occupancy class, and any conditions. New buildings and buildings undergoing major changes of use need one before they can be lawfully occupied.
For residential rentals, the C of O is what tells you whether a given apartment is a legal dwelling unit. Renting a space the C of O does not authorize as a residence — an illegally converted basement or a unit beyond the certified count — can mean the rent is uncollectible and the tenant has expanded protections.
It is keyed to the building (BIN) and is part of the public DOB record any diligent listing assembly should check.
Related terms
- Multiple DwellingA residence with three or more independent units — the threshold that triggers many NYC building-code and registration duties.
- BIN (Building Identification Number)A seven-digit NYC identifier for a single physical structure, distinct from the parcel-level BBL.
- BBL (Borough-Block-Lot)NYC’s unique parcel identifier — a borough digit plus block and lot numbers that pins a property to the tax map.
- Warranty of HabitabilityA non-waivable promise, implied in every NYC residential lease, that the apartment is fit to live in.
This definition is general information about a New York City rental or rent-regulation concept, not legal advice. The rules change and often turn on facts specific to a building, unit, and tenancy — confirm the current rule and consult a qualified attorney before acting on any individual matter.