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Child Support Interest Calculator

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.

To use the child support interest calculator:

  • Make sure that you have Microsoft Excel installed on your computer.
  • Go into the "Tools" menu and change the security settings to "Medium."
  • Download an Excel file of the calculator. This is a spreadsheet file that works only in Excel.
  • Open the file in Excel. You will get a dialog box that asks about macros. Select "enable macros."
  • Delete the data that the author put in to test the file.
  • The author suggests that you use either F12 or File > Save As and, at the bottom of the dialog box, save it as an excel template. That way, when you open up a new file using this template, you don't run the risk of changing the formulas.
  • Then, simply fill in the information from your case.
  • You have to select a tab on the bottom to record individual payments and get a sheet to print out.

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.

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