Due diligence is the ability of the buyer to inspect and review every aspect of the real estate before closing on the transaction. In Arizona, the due diligence period is typically the first 10 days after contract acceptance.Learn the right way to conduct due diligence during the inspection period. What tools are available to a buyer to assess the conditions of the home. The Arizona REALTORS® Residential Resale Purchase Contract Due Diligence Section: Inspection Period and Buyer Disapproval. Due diligence within real estate transactions refers to both the buyer and seller satisfying various aspects of a purchase contract before finalizing things. A comprehensive guide to earnest money deposits in Arizona, along with details on requirements, payments, disputes, and refunds.