SOUTHERN CALIFORNIA EDISON Co

Nature of Estimate Required. SCE follows the accounting principles for rate-regulated enterprises which are required for entities whose rates are set by regulators at levels intended to recover the estimated costs of providing service, plus a return on net investment, or rate base. Regulators may also impose penalties or grant incentives. Due to timing and other differences in the collection of revenue, these accounting principles allow a cost that would otherwise be charged as an expense by an unregulated entity to be capitalized as a regulatory asset if it is probable that such cost is recoverable through future rates; conversely the accounting principles require creation of a regulatory liability for amounts collected in rates to recover costs expected to be incurred in the future or amounts collected in excess of costs incurred and refundable to customers. In addition, SCE recognizes revenue and regulatory assets from alternative revenue programs, which enables the utility to adjust future rates in response to past activities or completed events, if certain criteria are met, even for programs that do not qualify for recognition of "traditional" regulatory assets and liabilities.

Accounting principles for rate-regulated enterprises also require recognition of an impairment loss if it becomes probable that the regulated utility will abandon a plant investment, or if it becomes probable that the cost of a recently completed plant will be disallowed, either directly or indirectly, for ratemaking purposes and a reasonable estimate of the amount of the disallowance can be made.

Key Assumptions and Approach Used. SCE's management assesses at the end of each reporting period whether regulatory assets are probable of future recovery by considering factors such as the current regulatory environment, the issuance of rate orders on recovery of the specific or a similar incurred cost to SCE or other rate-regulated entities, and

other factors that would indicate that the regulator will treat an incurred cost as allowable for ratemaking purposes. Using these factors, management has determined that existing regulatory assets and liabilities are probable of future recovery or settlement. This determination reflects the current regulatory climate and is subject to change in the future. SCE also considers whether any plant investments are probable of abandonment or disallowance.

Effect if Different Assumptions Used. Significant management judgment is required to evaluate the anticipated recovery of regulatory assets and plant investments, the recognition of incentives and revenue subject to refund, as well as the anticipated cost of regulatory liabilities or penalties. If future recovery of costs ceases to be probable, all or part of the regulatory assets, plant investments and/or liabilities would have to be written off against current period earnings. At December 31, 2023, the consolidated balance sheets included regulatory assets of $11.4 billion and regulatory liabilities of $10.2 billion. If different judgments were reached on recovery of costs and timing of income recognition, SCE's earnings may vary from the amounts reported.

Application to Southern California Wildfires

Application to 2017/2018 Wildfire/Mudslide Events

Recovery of SCE's losses realized in connection with the 2017/2018 Wildfire/Mudslide Events in excess of available insurance is subject to approval by regulators. Under accounting standards for rate-regulated enterprises, SCE defers costs as regulatory assets when it concludes that such costs are probable of future recovery in electric rates. SCE utilizes objectively determinable evidence to form its view on probability of future recovery. The only directly comparable precedent in which a California investor-owned utility has sought recovery for uninsured wildfire claims related costs is SDG&E's requests for cost recovery related to 2007 wildfire activity, where the FERC allowed recovery of all FERC-jurisdictional wildfire claims related costs while the CPUC rejected recovery of all CPUC-jurisdictional wildfire claims related costs based on a determination that SDG&E did not meet the CPUC's prudency standard. As a result, while SCE does not agree with the CPUC's decision, it believes that the CPUC's interpretation and application of the prudency standard to SDG&E creates substantial uncertainty regarding how that standard will be applied to an investor-owned utility in cost-recovery proceedings for wildfire claims related to fires ignited prior to July 12, 2019. SCE will continue to evaluate the probability of recovery based on available evidence, including judicial, legislative and regulatory decisions, including any CPUC decisions illustrating the interpretation and/or application of the prudency standard when making determinations regarding recovery of uninsured wildfire-related costs. While the CPUC has not made a determination regarding SCE's prudency relative to any of the 2017/2018 Wildfire/Mudslide Events, SCE is unable to conclude, at this time, that uninsured CPUC-jurisdictional wildfire-related costs for these events are probable of recovery through electric rates. SCE would record a regulatory asset at the time it obtains sufficient information to support a conclusion that recovery is probable.

Through the operation of its FERC Formula Rate, and based upon the precedent established in SDG&E's recovery of FERC-jurisdictional wildfire-related costs, SCE believes it is probable it will recover its FERC-jurisdictional wildfire and mudslide related costs and has recorded total expected recoveries within the FERC balancing account.

Application to Post-2018 Wildfires

Management judgment is required to assess the probability of recovery of SCE's losses realized in connection with the Post-2018 Wildfires in excess of available insurance.

The CPUC and FERC may not allow SCE to recover uninsured losses through electric rates if it is determined that such losses were not reasonably or prudently incurred. On July 12, 2019, AB 1054 clarified that the CPUC must allow recovery of costs and expenses arising from a covered wildfire if the utility's conduct related to the ignition was consistent with actions that a reasonable utility would have undertaken in good faith under similar circumstances, at the relevant point in time, and based on the information available at that time. Further, utilities with a valid safety

certification at the time of the relevant wildfire will be presumed to have acted prudently related to a wildfire ignition unless a party in the cost recovery proceeding creates "serious doubt" as to the reasonableness of the utility's conduct, at which time, the burden shifts back to the utility to dispel that doubt and prove its conduct was prudent. The serious doubt standard in AB 1054 is modeled after the FERC cost recovery standard. SCE evaluates the probability of recovery of costs related to the Post-2018 Wildfires in the context of the prudency standard laid out by AB 1054 above, including how the FERC applies the serious doubt standard. SCE’s evaluation also relies on its status as a holder of a valid safety certificate, facts and other evidence known to date related to the ignition, and any regulatory decisions illustrating the interpretation and/or application of the prudency standard under AB 1054, which as of December 31, 2023, has not been applied by the CPUC to an actual cost recovery application filed by any California investor-owned utility. SCE also considers which costs are eligible for recovery based on precedent from other CPUC cost recovery proceedings. Management's assessment of the probability of recovery may change, related to changes in any of these factors in the future.

See "Notes to Consolidated Financial Statements—Note 12. Commitments and Contingencies—Contingencies—Southern California Wildfires and Mudslides—Post-2018 Wildfires" for further discussion of regulatory assets recorded for Post-2018 Wildfires as of December 31, 2023.