Certificate of Occupancy (CO)
A Certificate of Occupancy (CO) is a document issued by the NYC Department of Buildings (DOB*) that states a building’s legal use and permitted occupancy. It may identify approved uses by floor and the number of dwelling units. New buildings need a CO, and certain changes to existing buildings require a new or amended CO. Some older buildings are exempt.
If you change how the building is used—for example, turning a store into an apartment or dividing one apartment into two—you may need a new or amended CO showing the approved change.
Simple example – adding a third apartment:
If your CO says “2‑family house.” – That means the City only allows 2 separate apartments in the building. If you create a third apartment in the basement and rent it without the required City approval, that extra apartment is illegal.
Does every NYC building need a CO?
Not every building has to have a Certificate of Occupancy. Buildings built before 1938 generally do not need one unless later alterations changed their use, egress, or occupancy. Egress means the way people exit the building.
If a building is exempt and you need proof of its legal use, contact the DOB borough office about a Letter of No Objection (LNO). An LNO is not a replacement for a CO when a CO is required.
Quick Facts:
- Who gives the CO? – NYC Department of Buildings (DOB*).
- What does it say? – If the building is a 1‑family house, 2‑family house, apartment building, store, office, etc., and sometimes how many people or families can be there.
- When do you need it? – New buildings need a CO before people move in or use them. Some changes to existing buildings also require a new or amended CO. Some older buildings are exempt.
- Why is it important? – It shows the building passed inspections and follows safety and zoning rules.
- Does a CO expire? – A final CO does not expire. However, changes to the building may require a new or amended CO.
- When do you need a new or amended CO? – You may need one when you change the building’s use, exit arrangements, or approved occupancy. Work that does not require a new or amended CO may receive a Letter of Completion instead.
How to look up your CO
Check BIS* for CO requests made before March 1, 2021
- Open the DOB Buildings Information System (BIS).
- Search for the property by address.
- On the Property Profile page, select “View Certificates of Occupancy”.
- Open an available PDF to view or print the certificate.
Check DOB NOW* for CO requests made on or after March 1, 2021
- Open DOB NOW and use the address search.
- Open the property’s profile.
- Select “Certificate of Occupancy” near the top of the page.
- Review the Certificate of Occupancy Details and Floor Use Records. Use the Print button to print a copy.
What if you cannot find a CO?
A missing online result does not, by itself, establish that the building is illegally occupied. Check whether the building qualifies for the pre-1938 exemption. If the records or legal use remain unclear, contact the DOB borough office for the property.
NEXT STEP
Check official NYC requirements and CO lookup instructions.
Good to know
This guide provides general educational information in plain English. It is not legal advice or a determination of a specific property’s legal occupancy. Check current DOB guidance and consult a registered architect, professional engineer, or attorney when appropriate.
Feel free to comment on this post
This is an advertisement box
If you see any capital letter abbreviations on this page or in an official letter you received from the city and you do not understand them, you can try to look them up on our NYC Violation Codes HUB page with the search tool.
Revised