All Illinois Courts must accept these forms. Scroll down below the chart for important information on how to fill out these forms.Specifically, the landlord will file a Complaint in the Circuit Court of Cook County. This page gives the basics of the eviction process. A foreclosure case may take several years to resolve in court. Throughout this process, tenants still have rights and responsibilities. Here is a quick guide on how to fill out an Eviction Complaint in Illinois. What is the Keep Chicago Renting Ordinance? The primary purpose of this form is to formalize the complaint of a landlord seeking repossession of rented property due to the tenant's failure to pay rent. It is illegal for Illinois landlords to retaliate against tenants for calling local authorities to complain about problems in a residential apartment.