NYC Certificate of Occupancy: When You Need One and Why It Affects Rent

When a NYC building needs a certificate of occupancy, what pre-1938 buildings have instead, how to find one, and why a missing CO can stop you collecting rent.

By Seayora Editorial Team · Published October 28, 2026 · Facts checked October 28, 2026 · 4 min read

Short answer: A certificate of occupancy (CO) states a building’s legal use, occupancy and egress, and in New York City no one may legally occupy a new building until the Department of Buildings issues a CO or a temporary CO. Existing buildings need a new or amended CO when their use, egress or type of occupancy changes. For multiple dwellings the stakes are financial: Multiple Dwelling Law § 302 bars an owner from recovering rent for a period of occupancy that violates the CO requirement.

Key takeaways

A new building, and any change in use, egress or type of occupancy, needs a certificate of occupancy or a temporary one.
Buildings built before 1938 generally were not required to have a CO; a Letter of No Objection can confirm a legal use.
Multiple Dwelling Law § 302 bars recovering rent, and a nonpayment case for possession, for unlawful occupancy of a multiple dwelling.
Find a building’s CO in DOB NOW for requests from March 1, 2021, or in the Buildings Information System for earlier ones.

What is a certificate of occupancy?

A certificate of occupancy is the Department of Buildings document that confirms a building’s legal use and occupancy. It records how the building may be used, for example how many dwelling units it has, and it is the baseline the department, lenders, insurers and courts compare the building against. The department says no one may legally occupy a building until it has issued a CO or a temporary certificate of occupancy (TCO) (NYC DOB: Certificate of Occupancy).

When does a building need a new or amended CO?

New buildings need one, and existing buildings must have a current or amended CO when there is a change in use, egress or type of occupancy. Converting a store to an apartment, adding a unit, legalizing a cellar space or turning a two-family house into a three-family house are typical triggers. Work that changes none of those three things, such as a kitchen renovation, usually does not require a new CO, although it may still require a permit.

What if the building was built before 1938?

Buildings built before 1938 are generally not required to have a certificate of occupancy, unless later work changed their use, egress or occupancy. Because there is no CO to show a lender or a buyer, the department can issue a Letter of No Objection to confirm the legal use of such a building where no CO was required at the time.

Why can a missing CO stop you collecting rent?

State law ties rent to lawful occupancy for multiple dwellings, meaning buildings occupied as the home of three or more families living independently (MDL § 4(7)). Multiple Dwelling Law § 301 prohibits occupying a multiple dwelling without a certificate of occupancy, and § 302 sets out the consequences of occupying one in violation of § 301:

No rent can be recovered by the owner for that period.
No action or special proceeding can be maintained for that rent, or for possession of the premises for nonpayment of it.
Any mortgage on the building may be declared due at the option of the mortgagee during the unlawful occupation.

Courts have applied the rent bar where the actual occupancy varies from what the certificate allows, not only where there is no certificate at all. If a building is rented as more apartments than its CO permits, talk to a lawyer before you start a nonpayment case, and talk to an architect about legalizing the space.

How do you find a building’s certificate of occupancy?

For certificates requested before March 1, 2021, search the address in the Buildings Information System (BIS) and choose “View Certificates of Occupancy” on the property profile. For those requested on or after March 1, 2021, search the address in DOB NOW and choose “Certificate of Occupancy” at the top of the property profile (NYC DOB). Compare the number of units, the floors and the uses on the certificate with how the building is actually occupied.

What should an owner check before buying or renting out a building?

The CO, TCO or Letter of No Objection, and whether a TCO has expired.
Whether the units, cellar and basement are occupied as the certificate describes.
Open permits and violations on the property profile, which can block an amended CO.
The zoning for the lot, if you plan to change the use; see NYC zoning explained.

Frequently asked questions

Can a NYC landlord collect rent without a certificate of occupancy?

For a multiple dwelling occupied in violation of the certificate of occupancy requirement, Multiple Dwelling Law § 302 says no rent can be recovered for that period and no nonpayment case for possession can be maintained. Get legal advice for your building.

Does a building built before 1938 need a CO?

Generally not, unless later alterations changed its use, egress or occupancy. The Department of Buildings can issue a Letter of No Objection to confirm the legal use of such a building.

What is a temporary certificate of occupancy?

A temporary certificate of occupancy (TCO) allows legal occupancy before the final CO is issued. Occupancy is legal only once the department has issued a CO or a TCO.

Sources

Certificate of Occupancy, NYC Department of Buildings
N.Y. Multiple Dwelling Law § 4, Definitions, New York State Senate
N.Y. Multiple Dwelling Law § 301, Certificates of occupancy, New York State Senate
N.Y. Multiple Dwelling Law § 302, Unlawful occupation, New York State Senate

How Seayora helps

Document storage: Keep the certificate of occupancy, permits and sign-offs with each property’s records.

This article is general information, not legal, architectural or engineering advice. Zoning, building, electrical and plumbing rules are amended by local law and agency rule and differ from one city, town and village to the next, so confirm the current requirements with the building department and a licensed professional before you start work.

How we write and check these guides: editorial standards.

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