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On August 7, 2026 Staff of the Illinois Commerce Commission (ICC) issued a  Staff Report regarding Ameren Supply-Delivery Cost Allocation Investigation that was byproduct of the utility’s most recent rate case.

The Staff Report said that “while Ameren’s allocation methodology is not without limitations,” the information reviewed by Staff and Ameren’s practices, “do not demonstrate a clear or material misallocation of costs between supply and delivery services that would warrant further Commission action at this time.”

Actions Staff Does Not Recommend

“Based on the information obtained in this investigation, Staff finds that while Ameren’s allocation methodology is not without limitations, the information and Ameren’s practices do not demonstrate a clear or material misallocation of costs between supply and delivery services that would warrant further Commission action at this time. ICEARESA raises concerns regarding the potential impacts of cost allocation on customer pricing, competitive markets, and CEJA-related outcomes. While these concerns are conceptually grounded in cost causation principles, ICEA-RESA does not identify specific cost categories that are improperly assigned between supply and delivery functions, nor does it demonstrate that Ameren’s current methodology results in a measurable or material misallocation of costs. Accordingly, Staff does not recommend that the Commission initiate a separate proceeding to further evaluate cost classification. Given the absence of identified misallocations, initiating an additional proceeding at this time would be premature, administratively inefficient, and may result in unnecessary use of Commission and stakeholder resources. Staff further finds that issues related to the assignment of costs between supply and delivery functions are inherently tied to the determination of the delivery service revenue requirement. As such, any proposed changes to Ameren’s allocation methodology would be more appropriately considered in the context of an MYRP or rate case proceeding, where the full revenue requirement and supporting cost structure would be subject to review.”

Actions Recommended by Staff

“While Staff does not recommend immediate changes to Ameren’s allocation methodology, Staff finds that certain areas would benefit from further evaluation in a future MYRP or rate case proceeding. Staff notes that Ameren has begun collecting data related to customer call center interactions, including categorization of customer inquiries based on the reason for the call. (Ameren response to Staff Data Request CNS 2.02, E, Appendix A.) The Company has also identified limitations associated with this data, including situations where customer inquiries involve multiple issues or where the appropriate classification of the call is unclear. (Ameren presentation, Workshop 1, Slide 18, Appendix C.) Staff finds that this data has the potential to provide additional insight into whether certain customer-related costs support both supply and delivery functions and may improve the ability to evaluate cost causation in future proceedings.

Accordingly, Staff recommends that Ameren, in its next MYRP or rate case filing, provide:

• a detailed narrative explaining its customer interaction tracking practices and the extent to which customer interaction data may be relevant to the evaluation of customer-related cost allocation issues.
• a description of the customer interaction data currently collected by the Company, including “reason for call” categories and identified limitations associated with the data;
• a discussion of any planned enhancements or refinements to the Company’s customer interaction tracking practices, including treatment of calls involving multiple issues or unclear categorization;
• an evaluation of whether customer interaction data may reasonably support future analysis of customer-related cost allocation methodologies;
• where the Company determines refinements are appropriate, an explanation of its proposed methodology, implementation approach, and supporting rationale; and
• an explanation of the principal customer-related cost categories supporting the Company’s allocation methodology, including the basis for assigning those functions to supply, delivery, or shared activities where applicable.

Staff further recommends that Ameren consider enhancements to its call center data collection practices, including the development of categories to capture customer interactions involving multiple issues or unclear classification. To the extent such categories are developed, the Company should evaluate reasonable and supportable methods for assigning those costs between supply and delivery functions, including approaches that reflect the underlying mix of activities associated with those interactions, such as customer mix or proportion of call types. At this time, Staff is not recommending that Ameren immediately incorporate customer interaction data into its allocation methodology.

Rather, Staff recommends that, in its next MYRP or rate case proceeding, Ameren presents its evaluation of the concerns identified through this investigation regarding customer-related cost allocation. Specifically, the Company should explain whether the information developed during this investigation, together with any additional analyses or data collected, supports continuation of its current methodology or whether refinements are appropriate. If Ameren determines that additional data collection, study, or refinement is necessary before reaching that conclusion, the Company should explain the basis for that determination, describe its proposed approach for addressing the identified limitations, and provide an anticipated timeline for completing that work. Conversely, if the Company concludes that its current methodology remains appropriate, it should explain the basis for that conclusion and how the concerns identified during this investigation were evaluated.”