An Illinois renttoown agreement is a fixedterm rental contract that gives tenants the right to buy the property they've been renting. Use our free, customizable Illinois lease agreement template to create a legally binding contract when you lease your Property in the state of Illinois.This interactive legal form creates a standard lease for a residential property, with provisions for the tenants to exercise an option to buy the property. This Lease to Purchase Option Agreement ("Option to Purchase Agreement") is made on. "A lease option is a contract in which a landlord and tenant agree that, at the end of a specified period, the renter can buy the property at a specified price. This form is an Option to Purchase, also known as a Lease Purchase Option. Edit, sign, and share Option to Purchase Addendum to Residential Lease - Lease or Rent to Own - Illinois online. Option to purchase: Landlord gives Tenant and exclusive right to purchase the property at a specified time for a pre-determined price. Drafting a comprehensive agreement is crucial. Purchase agreement is a standard lease with an added option for the tenant to purchase the property.