Use our free, customizable Illinois lease agreement template to create a legally binding contract when you lease your Property in the state of Illinois. An Illinois renttoown agreement is a fixedterm rental contract that gives tenants the right to buy the property they've been renting.You must submit Form ST-201, Rental Purchase Agreement Occupation Tax Return, to report and pay the Rental Purchase Agreement Occupation Tax. "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.