Briefs Filed in Electric Utility’s Rate Case

Parties filed initial briefs on October 26, 2026 in DTE’s rate case and include comments on establishing stand-alone large customer tariff and rate of return issues.

(1) Association of Businesses Advocating Tariff Equity (ABATE) recommended establishing separate classes for large load customers, arguing that: (i) doing so “benefits every existing customer class”; and (ii) “combining the large load customers into a single class… would socialize costs associated with one particular customer to the class”;

(2) ABATE argued that approval of DTE’s proposed “LLTM’ should be contingent upon DTE”: (i) “Modifying the termination date of the LLTM to the day prior to new base rates going into effect following DTE’s next general rate case proceeding”; (ii) “Making the required June 1, 2028 filing regarding the disposition of the of the LLTM regulatory liability, and any similar filing thereafter, a contested case filing to ensure the regulatory liability is returned to all customer classes in a manner consistent with cost-of-service principles; and (iii) “Filing quarterly compliance reports on the status, calculation and current balance of the LLTM regulatory liability”;

(3) Staff recommended MIPSC approve “a total rate base of $28.509 billion,” a reduction of $359.140 million from DTE’s initial projection;

(4) “Staff recommends [MIPSC] approve [DTE’s State Reliability Mechanism (SRM)] capacity revenue requirement and charge calculation methodology”;

(5) regarding DTE’s IRM proposal, Staff: (i) said its “preference is that detailed reasonableness and prudence reviews be conducted entirely within rate cases, not reconciliation cases”; (ii) “recommends that for March 1, 2028, and later, the rate of return associated with the IRM surcharge should be lower than the pretax rate of return (‘ROR’) approved… [in] this case, but no lower than the short-term debt rate that will also be approved”; (iii) recommends that “the surcharge calculation also be updated to use the correct depreciation rate of 4.0822%”; and (iv) recommends that “the final revenue deficiency as ordered by [MIPSC] be updated to exclude any capital expenditures that would be recovered through an IRM surcharge”; and

(6) Staff said that, while it “finds the concept of an LLTM useful given the uncertainty surrounding the large anticipated OACS load,” it recommends modifying the LLTM proposal as follows: (i) “the LLTM continues beyond the test period”; (ii) “an LLTM regulatory liability mechanism is also applied to the load associated with the special contracts with Google”; (iii) “an appropriate interest rate is applied to the LLTM regulatory liability accrual”; and (iv) “Staff’s substation cost adjustment is adopted.”