Complete the on-line application for free child support services if you live in Illinois and the dependent child(ren) lives with you. Federal law requires that states offer and provide child support services (IV-D services) to all families, not just those who receive public assistance.Use the alimony calculator below to estimate your spousal maintenance in Illinois. Download and complete Divorce, Child Support, and Maintenance forms from the Illinois Office of the Courts. How Is Child Support Calculated in Illinois? Usually, the judge will ask you to complete a Financial Affidavit before the court hearing date at which you present your evidence. Alimony Laws in IL determine spousal support based on marriage length, income disparity, and ability to be self-sufficient. What is maintenance? Maintenance is the term used in Illinois for alimony or spousal support. In a divorce in Illinois, both parents have a responsibility to financially support their children.