On June 19, 2007, I&M filed a petition with the Indiana Utility Regulatory Commission (IURC) for authority to increase its rates and charges for electric utility service and to establish and implement rate adjustment mechanisms to track certain matters. Requested trackers relate to reliability enhancement, demand-side management/energy efficiency programs, off-system sales margins, PJM, and environmental compliance. Subsequently, I&M made the base rate case filing on January 31, 2008. Parties agreed to a historic test year ended September 30, 2007, adjusted for changes that are fixed, known and measurable for ratemaking purposes and that will occur within 12 months following the end of the test year.

Existing rates were established by IURC order in Cause no. 39314 based upon a test year ending December 31, 1991, with an ROR of 8.78% and ROE of 12%.