What do I need first? An Illinois lease agreement is a prevalent contract performed during the transfer of rights related to a real estate property (apartment, condo, house, etc.).An Illinois rental application allows landlords to gather information on potential tenants and evaluate their eligibility. Description of Rental Property. The lease agreement should have a full and complete description of the property that is being included as part of the lease. Clarify private housing applications and lease requirements, and discover safety tips for finding legitimate rentals. Illinois lease agreements let a landlord and tenant come to an agreement over the renting of a property. Rent is commonly due on the 1st of the month. 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 Residential Lease Agreement Form is a legally binding document that outlines the lease agreement between a landlord and tenant.