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What each document can establish
A Certificate of Occupancy (CO) establishes legal use or occupancy. New buildings need one, and relevant changes to use, occupancy or egress—the ways people leave—can require a new or amended CO.
| Document | Meaning and condition |
|---|---|
| CO | Legal use or occupancy; compare the proposed activity with the actual record. |
| Temporary CO (TCO) | Temporary permission, not a final CO. |
| Letter of No Objection (LNO) | Legal-use confirmation under its applicable conditions; not a universal CO substitute. |
| Letter of Completion | Qualifying completed work that did not require a new or amended CO; not an LNO or blanket approval of the next use. |
The pre-1938 exception is conditional
Certain lawful pre-1938 buildings may have no CO unless later changes triggered the requirement. Age alone does not establish the position.
For an old office proposed for training, identify whether the supplied completion letter is actually the relevant DOB record and what work it covers. Then compare the intended classes, occupancy and alterations with the legal-use evidence; this does not calculate capacity or approve the proposal.
Where to look for CO requests
For CO requests before March 1, 2021, DOB directs users to BIS; for requests on or after that date, to DOB NOW. The cutoff concerns CO requests, not every kind of building record. Check the relevant property records for open applications, violations and required sign-offs as well as the certificate or letter.
Scope
- NYC DOB occupancy records only; no property, capacity, lease, fire, accessibility, sector or licence approval is supplied.
Next step
Identify the actual building document and confirm that its use and conditions fit the proposed operation.
Sources & review notes
New York City Department of Buildings
Passage, dates and research notes
official-guidance · CO, TCO, pre-1938 buildings and lookup
March 1, 2021
Read complete page. CO legal use/occupancy, new/amended CO conditions, TCO, pre-1938 limitations and BIS/DOB NOW records distinction. A property’s actual certificate and violations have not been reviewed.
New York City Department of Buildings
Passage, dates and research notes
official-guidance · Distinct purposes of LNO and Letter of Completion
Letter of Completion
Read complete body. LNO may confirm legal use under specified conditions; Letter of Completion is a different document for qualifying work that does not require a new/amended CO. Neither is a blanket substitute for a CO.
Detailed rule records (1)
NYC DOB describes the CO as establishing legal use/occupancy, with new/amended certificates for applicable building/use changes. TCO, LNO and Letter of Completion have different purposes and conditions.
Certificate of Occupancy Letter of No Objection or Letter of CompletionKeep this reading in your learning library.
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