— TL;DR

How to look up any NYC certificate of occupancy free, what to do when a pre-1938 building has none, and when a renovation forces you to amend the C of O.

01 · THE SHORT ANSWERHow to look up a certificate of occupancy free

Every NYC certificate of occupancy is public and free to view. Search the building's address in DOB's BIS system and open "Certificates of Occupancy" to download the PDF — newer certificates also appear in DOB NOW. And if a pre-1938 building has no C of O at all, that's normal, not a defect: buildings built before 1938 were never required to have one.

02 · WHAT IT ISWhat the C of O actually certifies

The certificate of occupancy states a building's legal use and occupancy — how many dwelling units, what each floor may be used for, and the maximum number of people. It's the document that says "this building may legally be used this way." Lenders, insurers, and buyers' attorneys check it because using a building outside its C of O (an illegal unit, a commercial use in a residential space) is a violation that can block financing and trigger vacate orders — the illegal basement apartment is the classic case.

03 · STEP BY STEPThe lookup

  1. Search the address in BIS to open the property profile.
  2. Open "Certificates of Occupancy." Every certificate and temporary certificate issued for the building is listed as a PDF.
  3. Check DOB NOW for certificates on recent jobs — new filings and their C of O activity live there. (Not sure which system? DOB NOW vs BIS.)
  4. Read the use lines, not just the header: unit counts and permitted uses per floor are where mismatches with reality show up.

04 · COMMON QUESTIONSQuick answers

The building has no C of O — is that a problem?

If it was built before 1938 and its use never changed, no — it's legally occupied without one. A Letter of No Objection (LNO) from DOB can document the legal use when a lender or buyer insists on paper.

What's a TCO?

A temporary certificate of occupancy lets a building be occupied while final items are completed. TCOs expire and must be renewed — an expired TCO on an occupied building is a real problem at closing and shows up in every attorney's search.

When does a renovation require a new C of O?

When the work changes use, egress, or occupancy — converting a two-family to a three-family, turning a storefront into an apartment, changing the number of units. That's an Alt-CO filing, and the job isn't legally done until the amended certificate issues. Fee and filing details are in the building permit guide.

05 · THE C OF O IS HALF THE STORYCheck the rest of the record

A clean certificate doesn't mean a clean building: violations, complaints, and open enforcement live on separate records. Run a free violation lookup to see them in one search, and if you own or manage the building, ViolationWatch's detection engine watches all of it continuously — use changes, complaints, violations, and stop-work orders — and alerts you the day something new appears. Start a 7-day trial.

Last updated: July 2026.

— Data & sources

The figures in this article come from ViolationWatch's analysis of New York City building-violation records — more than 15 million violations across DOB, HPD, ECB/OATH, 311 and DOT. Explore the full data, borough breakdowns, fine trends, and downloadable dataset in our NYC Building Violations Statistics report.

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