A house listed as a two-family may have a certificate of occupancy for one family, and a finished basement may have none at all. In New York City the certificate of occupancy (CO) is the Department of Buildings’ record of what a building may legally be used for, and it is the first document a buyer of a one-, two- or three-family house should read, ahead of the inspection report. This guide shows where to find the CO, open permits and violations on the city’s own portals, what “no certificate of occupancy” means on the pages that define it, and which questions belong with a home inspector, an attorney, an expediter or an architect or engineer.
We are Inspecwise, a New York State-licensed, InterNACHI-certified home inspection business based in South Ozone Park, Queens. An inspection under the state’s Standards of Practice does not decide whether a house is legal, so this guide is about the records that do. It describes what the city’s pages say; it is not legal advice, and your real-estate attorney decides how a record affects your contract.
What a certificate of occupancy tells you, and what it does not
The Department of Buildings (DOB) says a certificate of occupancy “states a legal use and/or type of permitted occupancy of a building.” No one may legally occupy a building until DOB has issued a CO or temporary CO, and an existing building needs a current or amended CO when its use, egress or type of occupancy changes. A CO confirms that the completed work complied with the law and that relevant violations were resolved. It does not expire, and DOB will not issue one while applications or violations on the property are open.
What a CO does not do is describe condition. It will not tell you whether the roof leaks or the boiler is near the end of its life, and it cannot speak to later work unless that work changed use, egress or occupancy and so needed an amended CO. In DOB NOW a CO opens with “Certificate of Occupancy Details and Floor Use Records,” so the use of each floor is written down. Read the basement and attic lines first.
A pre-1938 house with no certificate of occupancy
DOB’s CO page says buildings built before 1938 are not required to have one unless later alterations changed their use, egress or occupancy. For those buildings DOB can issue a Letter of No Objection to confirm legal use, which you request from the DOB borough office. So “no certificate of occupancy” on an older house is not by itself a finding of illegality, and it is not a clean bill either. It sends you to two questions: was the house altered after 1938 in a way that changed its use, and is there a Letter of No Objection or a later CO on file?
Older houses are common. In the city’s PLUTO tax-lot file (version 26v2), the share of one-, two- and three-family lots with a recorded year built before 1940 is about 92% in Manhattan, 71% in Brooklyn, 50% in Queens, 46% in the Bronx and 20% on Staten Island. PLUTO’s year built is a rounded estimate for older buildings, so read those as rough, and the Manhattan figure rests on only 5,599 lots. Our guide to the pre-war home inspection covers what else to expect from them. An example, not a case we handled: a 1925 two-family in Queens where DOB NOW shows no CO. The open questions are whether DOB holds a Letter of No Objection, whether a later job turned a one-family into a two-family, and whether the second kitchen appears on any record. Those answers come from DOB, not from the walk-through.
Where to look: the official portals for a certificate of occupancy and permits
DOB’s Find Building Data page points to two systems. The Buildings Information System (BIS) has a profile page for every New York City property that lists jobs and filings, occupancy information, complaints, violations and inspections, and it holds permits and job applications from before DOB NOW launched. The DOB NOW Public Portal holds applications submitted in DOB NOW, including certificates of occupancy. Items are marked active or resolved. Which one you use for the CO depends on the date of the CO request.
| Portal | What it shows | How to use it |
|---|---|---|
| DOB NOW Public Portal (DOB) | COs requested on or after 1 March 2021, other DOB NOW applications, certain violations | Search the address, open the Property Profile and select Certificate of Occupancy. If one was issued, the CO details and floor use records open in a new window. |
| Buildings Information System, BIS (DOB) | COs requested before 1 March 2021; older permits and job applications; complaints; violations; inspections | Use the Building Information Search by address. From the Property Profile, select View Certificates of Occupancy. |
| HPD Online | Complaints and violations, property registration, charges and litigation, block and lot information, vacate orders | Search the address on HPD Online. The city also keeps I-card images for NYC properties there. |
| ACRIS (Department of Finance) | Deeds and other recorded documents for Manhattan, Queens, the Bronx and Brooklyn from 1966 | Ownership paper, not legal use. Staten Island is not in the list on DOF’s ACRIS page; ask your attorney how it is searched. |
For drawings and plans, DOB takes record requests through DOB NOW and emails you when they are ready at the borough office. The portal screens change, so the steps above are the ones DOB publishes rather than a screen-by-screen tour.
NYC Open Data: the same records as datasets
NYC Open Data publishes much of this record as datasets you can search or download, which helps when you compare several houses. They split along the same line as the portals, the older system and the newer one, so you often need two to see the whole picture. Descriptions below are the city’s own.
| Dataset | What the city says it holds | Watch for |
|---|---|---|
| DOB Certificate Of Occupancy and DOB NOW: Certificate of Occupancy | The first holds COs issued from 12 July 2012 to March 2021. The second covers COs issued through the DOB NOW module released in March 2021, with job filing, BIN, address and CO status and issuance date. | The city says to use the second from March 2021 on. Older COs need BIS. |
| DOB Violations, DOB Safety Violations and DOB ECB Violations | Older civil penalties issued in BIS; newer civil penalties issued or payable in DOB NOW; and summonses issued by DOB and adjudicated by OATH/ECB. | Some violations appear in both civil-penalty datasets. ECB is a separate list. |
| DOB NOW: Build – Approved Permits and DOB Permit Issuance | Approved construction permits in DOB NOW (electrical, elevator and limited-alteration applications have their own datasets); and permits issued in BIS only. | Check both. Most current permits are issued in DOB NOW. |
| DOB Complaints Received | All complaints received by DOB, from 311 or entered by DOB staff. | A complaint is a report, not a finding. |
| Housing Maintenance Code Violations and Multiple Dwelling Registrations (HPD) | HPD violations in rental dwelling units and buildings, in classes A, B, C and I; and registrations of buildings with three or more units or of one- or two-family homes where neither the owner nor the owner’s immediate family lives there. | The city notes that an open violation may or may not have been corrected physically. |
Treat the datasets as a convenient copy and the portals as the lookup, and ask your attorney whether the searches ordered for your closing cover the same ground. According to the State Bar, a title report discloses outstanding property violations and permits among other items.
Open permits, violations and summonses: what each one means
| Record | What it can mean for a buyer | How it closes |
|---|---|---|
| Open permit or application | DOB will not issue a CO while applications or violations are open. | Final sign-offs, then a CO or Letter of Completion |
| DOB violation | Public, and it appears in a title search. DOB says open violations can prevent an owner from selling or refinancing, and it will not issue new or amended COs while DOB violations are active. | The condition is corrected and proof goes to the issuing unit |
| ECB or OATH summons | Stays open on the property profile until dismissed at a hearing or resolved by a certificate of correction, even if the penalty was paid. | Dismissal, or an approved certificate of correction |
| HPD violation | Issued for conditions in rental units and buildings; class A (non-hazardous), B (hazardous), C (immediately hazardous) or I (information orders). | HPD verifies correction, or the owner certifies it |
| DOB complaint | A report through 311 or by DOB staff; not a violation until an inspector issues one. | DOB records a disposition |
DOB lists who can file a certificate of correction: the owner, the respondent named on the summons, a contractor, a licensed professional, a filing representative or the preparer. Ask the seller for proof of correction, not a promise. DOB’s own warning is that unpermitted work “can lead to safety risks, violations, fines, and delays,” and most construction in the city needs DOB approval and permits, with some minor alterations exempt.
Legal use of one-, two- and three-family houses, basements and conversions
How many families a house may hold is a CO question. The table counts residential tax lots in the one-, two- and three-family classes in PLUTO, including the lots the Department of Finance classes as “two family converted from one family.”
| Borough | One-family lots | Two-family lots | Three-family lots | Two-family lots classed “converted from one family” (share) | Year built before 1940 (share) |
|---|---|---|---|---|---|
| Queens | 150,637 | 96,302 | 23,991 | 34,190 (36%) | 50% |
| Brooklyn | 61,349 | 94,710 | 34,174 | 19,797 (21%) | 71% |
| The Bronx | 21,413 | 29,465 | 11,092 | 4,747 (16%) | 46% |
| Manhattan | 2,336 | 1,867 | 1,396 | 370 (20%) | 92% |
| Staten Island | 76,985 | 31,349 | 872 | 2,863 (9%) | 20% |
Source: NYC Department of City Planning, PLUTO version 26v2, residential lots in building classes A, B and C0. The conversion class (B3) is a Department of Finance building classification used for taxes. It is the assessor’s category, not proof that a conversion was permitted or that the CO matches. In Queens, 34,190 two-family lots, about 36%, carry it; the CO says what the conversion legally became.
Two-family, three-family and the basement unit
A three-family is a multiple dwelling, and owners of buildings with three or more units, or of one- or two-family homes where neither the owner nor immediate family lives there, must register annually with HPD. Adding a unit changes the building type: DOB’s ancillary dwelling unit page says a two-family building adding an attic, basement, cellar or attached unit is treated as a three-family building under the Multiple Dwelling Law unless the unit is separated by a fire wall, and HPD says a basement in a two-family house cannot lawfully be rented if that would make it a multiple dwelling needing a new certificate of occupancy. So a “two-family with a basement apartment” may legally be a three-family, a different building type with a different CO.
Basements and cellars
HPD’s basement and cellar page says basements and cellars in residential buildings of all sizes can never be lawfully rented or occupied unless they meet minimum light, air, sanitation and egress requirements and have DOB approval, and tells renters to check the CO on DOB’s site. It says cellars in one- and two-family homes can never be lawfully rented, and that HPD and DOB can both issue violations and vacate orders. The city has since created a limited pathway: DOB’s ancillary dwelling unit page, last revised on 9 April 2026 when we read it, covers new subgrade units outside the high-risk flood areas it lists and a pilot for existing units in listed community districts, including Queens community district 2. That pilot was not accepting applications until DOB writes its rules. Rules may have moved, so confirm the address, the flood area and DOB’s current position before assuming a basement apartment can be legalized. Our guide to basement inspections covers the physical side.
| House type | Pull these records | Ask these questions |
|---|---|---|
| One-family | CO or Letter of No Objection; permits for any addition, finished basement or attic; open violations | Does the CO match what is built? Is there a second kitchen, entrance or meter? |
| Two-family | CO showing two families; HPD registration if the owner does not live there; permits for any third unit | Is the basement or attic unit on the CO? Is it rented? |
| Three-family | CO showing three families; HPD registration and violations; permits for alterations | Do the units match the CO? Who is on the registration? |
| Basement or cellar apartment | CO showing the unit; DOB approval; HPD violations and vacate orders | Does it meet the HPD minimums? Is the address in a flood area that blocks subgrade units? |
If you are selling, run the same search first; it is the start of a seller’s inspection or a pre-listing inspection (see our pages for Queens, Brooklyn and the Bronx). Our page on two- and three-family home inspections covers houses with several units.
What an inspection report says about legal use and permits
The Standards are plain. A home inspector shall not determine compliance with regulations, codes, laws or ordinances, shall not determine boundary lines, easements or limits on use, and, under 197-5.16, need not report past or present code violations. Every inspection agreement must also say that home inspectors may not provide engineering or architectural services. An inspector cannot tell you the house is legal, that an addition was permitted, or that a basement apartment can be rented.
What an inspector can do is describe what is physically there and say what could not be seen. A report that records a second kitchen, bedrooms in a basement, two electric meters or a separate entrance gives you the facts the CO has to explain. So the order matters: pull the CO and permits first, walk the house with them in hand, and send both to your attorney.
When to call an attorney, an expediter, or an architect or engineer
- Your attorney for the contract. The State Bar’s guide lists questions an attorney helps with: whether an altered property still complies with the building code, whether the zoning allows a two-family house, and what the title report shows, since a title search says nothing about zoning. Ask what your contract says about open violations and a mismatched CO before the inspection contingency ends. Our guides to property condition disclosure and the home inspection contingency cover the seller’s statement and the clock.
- An expediter, someone hired to handle filings and follow-up with DOB, for paperwork that needs chasing: finding records, closing out permits, submitting a certificate of correction. An expediter does not replace a design professional where plans are needed.
- An architect or engineer, specifically a registered design professional (a Professional Engineer or Registered Architect), because DOB says only one can submit construction documents. Legalizing an unpermitted conversion starts with having one file plans and receive DOB approval. For a crack or a sagging floor rather than a record, see the home inspector versus structural engineer guide.
- A licensed trade for repairs that need one. In New York City, electrical installation and modification requires a permit and a Licensed Master Electrician, and ordinary plumbing work that needs no permit must still be done by a Licensed Master Plumber.
Outside New York City: Nassau, Suffolk and Westchester
These portals are New York City’s. Outside the five boroughs, the state’s Uniform Code leaves the work to the local authority: the town, village or city building department issues the CO or certificate of compliance, and permission to use or occupy a building after a permit or change of use is granted only by one of them (19 NYCRR 1203.3). There is no single county portal, so a buyer asks the building department for the exact municipality for the CO, open permits and violations. Our pages for Nassau, Suffolk and Westchester describe the local housing.
A short list to run before you sign
- Look the address up on DOB NOW and BIS, and open the certificate of occupancy and its floor use records. If there is none, find out why: a pre-1938 exemption, a Letter of No Objection, or a gap.
- List open permits, DOB violations, OATH summonses and HPD violations, and note which are active.
- Compare the CO to the house: kitchens, bedrooms, meters, entrances, finished basement and attic.
- Ask the seller for permits and sign-offs for any addition, conversion, boiler, electrical or plumbing work.
- Send what you found to your attorney before the inspection contingency ends, then book the inspection so the report and the paper can be read together.
Short answers
How do I look up a certificate of occupancy in NYC?
For a CO requested on or after 1 March 2021, search the address in DOB NOW, open the Property Profile and select Certificate of Occupancy. For earlier ones, use the Building Information Search in BIS and select View Certificates of Occupancy, as described on DOB’s certificate of occupancy page.
Does a house built before 1938 need a certificate of occupancy?
DOB says buildings built before 1938 are not required to have one unless later alterations changed use, egress or occupancy. DOB can issue a Letter of No Objection to confirm legal use, which you request from the borough office.
Can I buy a house with open violations?
DOB says open violations can prevent an owner from selling or refinancing, and that DOB violation information appears in a title search. Whether the seller must clear them before closing depends on your contract, so ask your attorney before the inspection contingency ends.
Is a basement apartment legal if the house has a two-family certificate of occupancy?
Not necessarily. HPD says a basement can be lawfully occupied only if it meets the light, air, sanitation and egress requirements and has DOB approval, and that renting a basement in a two-family house is not lawful if it would make the building a three-family needing a new CO. Read the CO’s floor use records.
Will a home inspector tell me whether the work was permitted?
No. The Standards say a home inspector shall not determine compliance with codes, laws or ordinances and is not required to report violations. The inspector can describe what is built; the DOB records say whether it was approved.
Read the records, then book the inspection
Once the records are in hand, the inspection can read against them. We inspect in the five boroughs, Nassau, Suffolk and Westchester, and elsewhere on request, and we work in English, Urdu, Punjabi and Hindi. Our inspections follow the NYS Standards of Practice, so we report what we can see and say plainly what falls outside them, including whether a house is legal.
Questions before you book? Call 718-925-7071.
About the figures: lot counts and the share of lots built before 1940 are from NYC PLUTO version 26v2 (NYC Department of City Planning, via NYC Open Data), counting residential tax lots in building classes A, B and C0. Dataset descriptions are quoted from NYC Open Data as read on 26 October 2026.