A purchase and sale agreement (PSA) is the binding contract setting price, deposits, contingencies, and closing terms.
The PSA turns the earlier LOI into a binding agreement. It sets the price, deposit, due diligence rights, closing date, representations, and what happens if either party defaults. Critical items for a NNN buyer include required estoppels, the seller's disclosure of lease documents, and any financing or 1031 exchange contingencies. Because the PSA controls the transaction, have a real estate attorney review it before you sign, and calendar every deadline.