The Illinois Class 4 Not-For-Profit Affidavit is a document that is filed with the Illinois Secretary of State. This document is necessary for organizations that wish to become a not-for-profit corporation in the state of Illinois. This document is intended to provide the Secretary of State with information about the organization's purpose and activities, financial data, and other pertinent information. There are two types of Illinois Class 4 Not-For-Profit affidavits: the Certificate of Organization and the Application for Registration. The Certificate of Organization is used to form a new not-for-profit corporation, while the Application for Registration is used to register an existing not-for-profit corporation. Both documents must be filled out and signed by the appropriate parties and filed with the Secretary of State.