NYC Affordability

The Certificate of Occupancy is the NYC Department of Buildings’ record of what a building is legally allowed to be used for and how many units it’s allowed to contain — residential, commercial, mixed-use, manufacturing, and so on. A building generally can’t be legally occupied without a valid C of O (or, for older buildings, an equivalent occupancy record) that actually matches its real-world use.

This matters most for converted buildings: a pre-war factory turned into residential lofts, or a building where a unit count was informally added without amending the paperwork, can end up with a C of O that doesn’t match reality. That mismatch typically surfaces during a title search, and it isn’t cosmetic — it can complicate financing, insurance, and resale until it’s fixed with an architect and a DOB filing. Some buildings also operate for years under a Temporary Certificate of Occupancy (TCO) rather than a final one, which is worth specifically asking about before buying.

Worked example

A buyer under contract on a loft in a converted manufacturing building discovers during attorney review that the C of O still lists “manufacturing” use, not residential. Resolving it can take months and require an architect and DOB expeditor — exactly the kind of issue an attorney review period exists to catch. See NYC closing costs for buyers for where attorney review fits in the purchase timeline.