The Lease Effective Date is an important date for keeping track of a business lease agreement. It marks the official start date of the lease, and any changes or modifications made to the agreement that occur after this date are generally considered not applicable or binding. The Lease Effective Date is usually determined by both parties to the lease agreement and should be accurately noted in the contract. All payments due pursuant to the lease agreement (such as rent) start on this date and must be paid from this point forward.