What is a Certificate of Occupancy?

by | Last updated May 10, 2024 | General Architecture, NYC DOB

What is a Certificate of Occupancy?

A Certificate of Occupancy is a document that describes the legal use and maximum occupancy of a building issued by the Department of Buildings. The Certificate lists individual building uses per story, the maximum occupancy of each space, construction classification, and various other building designations.

Below is an example of a two-page Certificate of Occupancy for a two-family home in New York City.

Certificate of Occupancy Building Information

Certificate of Occupancy Building Information Page


Certificate of Occupancy Use Description

Certificate of Occupancy Use Description


Certificate Of Occupancy 

The Department of Buildings issues a certificate Of Occupancy (also known as a “CO” or “C of O”) to identify the legal use of a building. The DOB will issue the Certificates Of Occupancy at the completion of a New Building (or house) or Alteration to a building (or Home) requiring a new Certificate of Occupancy. They issue the Certificate after the completion of construction, all the necessary inspections, and completion of all paperwork. Obtaining a Certificate Of Occupancy requires coordination and a thorough review of the building.


What Information is on a Certificate Of Occupancy?

  • General Building Information
  • Certificate Type
  • Applicable Building Code
  • Building Construction Classification
  •  Building Occupancy Group
  • Multiple Dwelling Law Designation (if applicable)
  • Building Size
  • Description of Fire Protection Systems
  • Type and number of open spaces
  • Additional Limitations / Restrictions
  • List Of Floors with:
    • Maximum number of persons per space
    • Structural live load per floor
    • Building Code Occupancy Group
    • Number of Dwelling or Rooming Units
    • Zoning Use Group per space
    • Description of Each Use


Video Explaining A Certificate of Occupancy



How to Read a Certificate Of Occupancy

The following explanation is based on a typical New York City Certificate of Occupancy. The details may differ in different cities or counties. Older Certificates may vary as well.


Certificate of Occupancy Number and Statement

At the top of a CO, you will see “Certificate of Occupancy” in large letters.

On the Certificate of Occupancy, you will see a “CO number” This is the number of the specific property’s Certificate. If this ends with an F, it is a final Certificate of Occupancy. We will get back to this distinction later in this blog post.

The Page Count is located at the top right-hand corner. A CO for a single-family house may be only two pages, but a large building could easily be 5 to 10 pages.

A paragraph at the top explains what a Certificate of Occupancy means.

“This certifies that the premises described herein conforms substantially to the approved plans and specifications and to the requirements of all applicable laws, rules, and regulations for the uses and occupies specified. No change of use or Occupancy shall be made unless a new certificate of Occupancy is issued. This document or a copy shall be available at the building for inspection at all reasonable times”

General Building Information

The Certificate of Occupancy always starts with general building information.

Borough & Address

The first piece of information on a CO in NYC is the Borough: Manhattan, Bronx, Brooklyn, Queens, or Staten Island.

Below the borough is the property address.

Building Information Number

Every building in NYC has a Building Information Number or BIN. These are specific numbers to identify the building in the Department of Buildings System. If you are researching records on a property, check if it has an old obsolete BIN for historical records. Empty lots do generally not have BIN numbers. The Department of Buildings (DOB) issues the Building Information Number (BIN). All this information is available on the NYC DOB BIS or Building Information System.

Block and Lot

The Certificate of Occupancy will list the Block and Lot. Every block has a Block Number, and every lot within a Block has a Lot Number. The Department of Finance (DOF) issues these numbers.

Building Type

The Building type will be New or Altered. 

Type of Certificate of Occupancy

A Certificate of Occupancy can be a Temporary or Final Certificate. If there is a minor pending issue holding up the Final Certificate, but the building is otherwise ready to be occupied, you can apply for a temporary Certificate of Occupancy. You must renew the Temporary Certificate regularly or replace it with a Final Certificate of Occupancy.

Effective Date 

The Effective Date is the day of issuance of the CO. If you have a Temporary Certificate of Occupancy, there will also be an expiration date. In NYC, this is typically three months from the Effective Date.

Building Code

A statement usually says, “This building is subject to this building code:” followed by the applicable code. This will indicate the date the application was filed and what code it was reviewed on. If it is an existing building alteration, it may qualify under older building codes depending on the case. 

Construction Classification

The Construction Classification is the type of construction a building is made of. The current codes identify Construction Classification I – V. These designations differ for buildings built under older codes.

Building Occupancy Group 

The Building Code identifies all types of building uses into occupancy groups. An Occupancy Group is different from a Zoning Use Group. The Building Occupancy Group will determine what codes apply to the building.

Multiple Dwelling Law

If the building is a Multi-family residential building in NY, it will have a Multiple Dwelling Law classification. Otherwise, this will not be applicable.

Number of Stories

The Number of Stories within the building is listed on a Certificate of Occupancy. A cellar, mezzanine, or roof does not count as a story.

Building Height

The building height is on the CO document.

Number of Dwelling Units

The number of dwelling units will be listed if the building is a residential building.

Fire Protection Equipment

The Certificate of Occupancy will list all the fire protection equipment in the building, if there is any, including fire alarms, sprinklers, standpipes, etc.

Open Spaces

The document also lists the type and number of open spaces on the property. These can be outdoor parking spaces, plazas, outdoor eating, etc.


“The Certificate is issued with the following legal limitations.”

There is an area for legal limitations and restrictions. These can be many things, such as a Restrictive Declaration. The limitations will vary from building to building.

Outstanding Requirements

If the Certificate issued is temporary, this section will be filled in, listing the number of outstanding items. This section should be blank if a Final Certificate of Occupancy were issued.

Borough Comments

Each of the five boroughs in NYC has its own Department of Buildings Borough Office. These offices issue the Certificates of Occupancy. The document may have comments, but this section is often blank.

 Permissible Use and Occupancy

The Use and Occupancy section is based on the Schedule A supplied by the Architect of Record on the project. This lists all the floors with their legal use and Occupancy. This section is a chart showing the following information.

Floors From To

In cases where consecutive floors are the same, it will be a floor range.

Maximum Persons Permitted

The maximum persons will be listed if there is a limitation to the number of people per floor or space. For example, a theater or restaurant would list the maximum number of people allowed.

Live Load

Live load is a structural engineering term for the amount of weight the engineer must use to determine what the floors must support. ThiLive load does not count building materials and structure. It is the weight of people and typical furniture and nonstructural elements. A library may have a high live load to support all the books, shelves, and people.

Building Code Occupancy Group

If you have a mixed-use building, all the spaces are identified with separate occupies. These are the building code Occupancy Groups that determine what codes apply. Occupancy Group is different from the Zoning Use Group.

Dwelling or Rooming Units

Dwelling units are apartments; rooming units can be hotel rooms or dorms. If applicable, the number of units per floor are listed on the Certificate of Occupancy. There was a period of time when the COs in NYC recorded the number of rooms in the apartments, but this is no longer done for new COs. you may encounter older Certificates with this information still listed.

Zoning Use Group

The Certificate of Occupancy lists the Zoning Use Group for each space or floor within a building. Use Group is separate from the Building Code Occupancy Group. Zoning codes and building codes are two completely different things.

Description of Use

Each floor or space will have a brief description. These should be concise and to the point. I have seen some terribly written Certificates of Occupancy, so we always try to make sure this is written clearly. The architect writes this, and the DOB approves it. The wording does not come from DOB.

Additional Information

At the end, there is a section for additional information. This could be anything from Easements to special notes.

DOB Signatures

The Commissioners of the Department of Buildings will sign the bottom of the Certificate.


Requirements for a Certificate of Occupancy in NYC

Below is a list of some of the items that may be required to obtain a Certificate Of Occupancy.

  • Final Construction inspection Sign-off
  • Final Plumbing inspection Sign-off
  • Elevator Sign-off
  • Electrical Inspection Sign-off
  • Special Inspections Sign Off
  • Progress Inspections Sign Off
  • EN2 As Built Energy Analysis
  • Final Survey
  • Builders Pavement Plan
  • Property Address from Borough President’s Office
  • No open applications
  • No open violations
  • Owner’s Cost Affidavit 

Alteration CO and New Buildings

The DOB will issue a Certificate Of Occupancy for 1 of 2 project types: New Buildings or Alteration CO, formerly known as an Alt 1 or Alteration Type 1.

New Building

All new buildings must obtain a C of O to be occupied. This involves filling a NB New Building application with the NYC Department of Buildings.

Alteration CO 

An Alteration CO (formerly Alt 1) is filed for any alteration that requires a New Certificate Of Occupancy. This is any alteration where there is a change in Use, Occupancy, or Egress.


Letter Of No Objection or LNO

If you own a building that does not have a Certificate Of Occupancy, you can file a Letter Of No Objection or LNO with the NYC DOB to determine if the proposed use requires a new Certificate Of Occupancy. An LNO is not a permit. It just states that the DOB does not object to the proposed use. You will file construction work separately for permits.

Letter of Verification or LOV

If you own a building with a Certificate Of Occupancy but are unsure if a specific use is covered, you can file a Letter of Verification or LOV with the NYC DOB to determine if the proposed use requires a new Certificate Of Occupancy. A LOV is not a permit. The DOB verifies the proposed use is covered under the existing CO. You will file construction work separately for permits.


Temporary Certificate Of Occupancy

Upon request, the DOB will issue a Temporary Certificate Of Occupancy or TCO before a final Certificate Of Occupancy. This is usually done when there are some open items on the building that are not critical for the C of O. Below is a list of some things that may be required to obtain a Temporary Certificate Of Occupancy.

  • Temporary or Final Construction inspection sign-off
  • Temporary or Final Plumbing inspection sign-off
  • Temp or Final Electrical inspection sign-off
  • Temp Elevator sign-off (if applicable)
  • TCO Fees


NYC Certificates Of Occupancy

As an architect, I study NYC building protocols, which are complicated and quite involved. In this article, we reviewed some of the basic concepts concerning a Certificate Of Occupancy. This post does not assume to cover every possible issue or condition, but provides a general overview of the topic.


Thank you for reading our blog post on What is a Certificate Of Occupancy.

I hope this was helpful. If you want to speak with an architect about a potential project, contact us at Fontan Architecture directly.


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Jorge Fontan

Jorge Fontan

This post was written by Jorge Fontan AIA a Registered Architect and owner of New York City architecture firm Fontan Architecture. Jorge Fontan has earned 3 degrees in the study of architecture including two degrees from the City University of New York and a Masters Degree in Advanced Architectural Design from Columbia University. Jorge has a background in construction and has been practicing architecture for 20 years where he has designed renovations and new developments of various building types.