A due diligence period is the set window after a purchase agreement is signed and before closing when a buyer investigates a multifamily property. During this period, teams verify the property’s physical condition, financials, leases, legal standing, and other risks before deciding whether to proceed, renegotiate, or terminate the deal. In multifamily acquisitions, this window is often measured in weeks and may include unit walks, document review, inspections, and operating-data validation.