File an annual report for a Corporation, Not-for-Profit, or Limited Liability Company online. Incorporate a business or terminate an LLC.You'll need to register your business with the state, prepare internal corporate documents, appoint company directors, and issue stock. Once filed with the state, this document formally creates your Illinois corporation. Learn how to start an S Corp in Illinois, file an LLC, and set up your business. Get step-by-step guidance on starting your business today. To form a corporation in Illinois, one of the first legal steps you need to take is filing articles pertaining to incorporating in Illinois. What is the Legal Name of your Corporation, Partnership, Limited Partnership, LLC, or Not-For Profit. Corporation?