Due diligence is the process in which a buyer conducts an in-depth investigation of a potential property acquisition. The buyer investigates everything that could affect the value, timeline, or feasibility of the deal: title, to confirm clean ownership; a survey, to verify lot boundaries; an environmental assessment, to check for contamination; and a zoning review, to confirm what can actually be built. They also pull all existing leases to understand tenant rights and rent stabilization exposure, and run a violations search through the NYC Department of Buildings and Environmental Control Board to uncover anything that could delay permits or require costly repairs before closing. In an NYC development site transaction, due diligence typically runs 30 to 60 days from contract signing. More complex sites with environmental issues, multiple tenants, or title difficulties can run longer. The timeline is usually negotiated upfront and written into the contract.

Example: A buyer under contract on a 7,500 SF lot in East New York discovers two open DOB violations totaling $45,000 in fines, three rent-stabilized tenants with no lease expiration for another four years, and a Phase I environmental flag from a former auto repair shop. Together, those findings prompted a $600,000 price reduction and a 30-day extension to the due diligence period before the buyer agreed to proceed.