ISBA does not warrant the accuracy of this calculator; use it as a guide only.
Effective January 1, 2006, PA 94-0089 imposes interest on overdue spousal maintenance obligations, including unallocated-support-and-maintenance obligations. A companion statute, PA 94-0090, changes the formula for calculating interest.
Illinois HFS has created a child support interest calculator based on the new formula as a Microsoft Excel document.
Here is a sample version of the calculator with data included.
Please note: this spreadsheet contains multiple formulas. In order to avoid modifying or deleting those formulas, we suggest that you only use the cells that are torquoise in color. These are the cells that are designed for you to input the case information. Also, in order to prevent any unintentional modification of the formulas, you should select "Protection" from the "Tools" menu and protect each sheet of the workbook. This will enable the "locked" feature of the cells containing formulas.