We show the details of regulatory assets and liabilities in the following table and discuss them below. With the exception of regulatory balancing accounts, we generally do not earn a return on our regulatory assets until such time as a related cash expenditure has been made. Upon the occurrence of a cash expenditure associated with a regulatory asset, the related amounts are recoverable through a regulatory account mechanism for which we earn a return authorized by applicable regulators, which generally approximates the three-month commercial paper rate. The periods during which we recognize a regulatory asset while we do not earn a return vary by regulatory asset.


REGULATORY ASSETS (LIABILITIES) AT DECEMBER 31
(Dollars in millions)
	Sempra				SDG&E				SoCalGas
	2023		2022		2023		2022		2023		2022
Fixed-price contracts and other derivatives	$	215	$	(56)	$	14	$	(110)	$	201	$	54
Deferred income taxes recoverable in rates	1,142		535		626		296		430		161
Pension and PBOP plan obligations	(212)		(159)		48		11		(260)		(170)
Employee benefit costs	24		29		3		5		21		24
Removal obligations	(3,082)		(2,864)		(2,468)		(2,248)		(614)		(616)
Environmental costs	139		145		105		107		34		38
Sunrise Powerlink fire mitigation	124		123		124		123		—		—
Regulatory balancing accounts(1)(2):
Commodity – electric	(233)		220		(233)		220		—		—
Commodity – gas, including transportation	(259)		(197)		52		60		(311)		(257)
Safety and reliability	959		682		207		107		752		575
Public purpose programs	(273)		(227)		(144)		(69)		(129)		(158)
Wildfire mitigation plan	685		375		685		375		—		—
Liability insurance premium	113		122		90		99		23		23
Other balancing accounts	373		65		(152)		(50)		525		115
Other regulatory (liabilities) assets, net(2)	(10)		301		49		132		(58)		169
Total	$	(295)	$	(906)	$	(994)	$	(942)	$	614	$	(42)

(1) At December 31, 2023 and 2022, the noncurrent portion of regulatory balancing accounts – net undercollected for Sempra was $1,913 and $1,254, respectively, for SDG&E was $950 and $562, respectively, and for SoCalGas was $963 and $692, respectively.

▪Regulatory assets arising from fixed-price contracts and other derivatives are offset by corresponding liabilities arising from purchased power and natural gas commodity and transportation contracts. The regulatory asset is increased/decreased based on changes in the fair market value of the contracts. It is also reduced as payments are made for commodities and services under these contracts. The related amounts are recovered in rates once these contracts are settled, generally within four years.

▪Deferred income taxes recoverable/refundable in rates are based on current regulatory ratemaking and income tax laws. SDG&E, SoCalGas and Sempra Infrastructure expect to recover/refund net regulatory assets/liabilities related to deferred income taxes over the lives of the assets, ranging from 5 to 69 years, that give rise to the related accumulated deferred income tax balances. Regulatory assets and liabilities include excess deferred income taxes resulting from statutory income tax rate changes and certain income tax benefits and expenses associated with flow-through items, which we discuss in Note 8.

▪Regulatory assets related to environmental costs represent the portion of our environmental liability recognized at the end of the period in excess of the amount that has been recovered through rates charged to customers. We expect this amount to be recovered in future rates as expenditures are made.

▪The regulatory asset related to Sunrise Powerlink fire mitigation is offset by a corresponding liability for the funding of a trust to cover the mitigation costs. SDG&E expects to recover the regulatory asset in rates as the trust is funded over a remaining 46-year period.

▪Over- and undercollected regulatory balancing accounts and other regulatory assets, net, reflect the difference between customer billings and recorded or CPUC-authorized amounts. Depreciation, taxes and return on rate base may also be included in certain accounts. Amounts in the balancing accounts are recoverable (receivable) or refundable (payable) in future rates, subject to CPUC approval. SDG&E and SoCalGas periodically make requests to the CPUC to true up their revenue requirement for amounts accumulated in the regulatory balancing accounts and in other regulatory assets, net. The CPUC may impose various review procedures before authorizing recovery or refund of amounts accumulated for authorized programs, including limitations on the program’s total cost, revenue requirement limits or reviews of costs for reasonableness. These procedures could result in delays or disallowances of recovery from customers.

Amortization expense on certain regulatory assets for the years ended December 31, 2023, 2022 and 2021 was $12 million, $11 million and $10 million, respectively, at Sempra, $6 million, $5 million and $5 million, respectively, at SDG&E, and $6 million, $6 million and $5 million, respectively, at SoCalGas.

In September 2019, the CPUC issued a final decision in the 2019 GRC approving SDG&E’s and SoCalGas’ test year revenues for 2019 and attrition year adjustments for 2020 and 2021, which was effective retroactively to January 1, 2019. This is the first GRC that includes revenues authorized for risk assessment mitigation phase activities. In January 2020, the CPUC issued a final decision implementing a four-year GRC cycle for California IOUs. SDG&E and SoCalGas were directed to file a petition for modification to revise their 2019 GRC to add two additional attrition years, resulting in a transitional five-year GRC period (2019-2023). In May 2021, the CPUC issued a final decision approving SDG&E’s and SoCalGas’ request to continue their authorized post-test year mechanisms for 2022 and 2023. For SDG&E, the decision authorizes revenue requirement increases of $87 million (3.92%) for 2022 and $86 million (3.70%) for 2023. For SoCalGas, the decision authorizes revenue requirement increases of $142 million (4.53%) for 2022 and $130 million (3.97%) for 2023.

In May 2022, SDG&E and SoCalGas filed their 2024 GRC applications requesting CPUC approval of test year revenue requirements for 2024 and attrition year adjustments for 2025 through 2027. SDG&E and SoCalGas requested revenue requirements for 2024 of $3.0 billion and $4.4 billion, respectively. SDG&E and SoCalGas proposed post-test year revenue requirement changes using various mechanisms that are estimated to result in annual increases of approximately 8% to 11% at SDG&E and approximately 6% to 8% at SoCalGas. Intervening parties have proposed various adjustments to SDG&E’s and SoCalGas’ revenue requirement requests. In October 2022, the CPUC issued a scoping ruling that set a schedule for the proceeding, including the expected issuance of a proposed decision in the second quarter of 2024. The CPUC has authorized SDG&E and SoCalGas to recognize the effects of the GRC final decision retroactive to January 1, 2024.

In October 2023, SDG&E submitted a separate request to the CPUC in its 2024 GRC describing $2.2 billion in costs to implement its wildfire mitigation plans from 2019 through 2022, and seeking review and recovery of the incremental wildfire mitigation plan costs incurred during that period, totaling $1.5 billion. SDG&E expects to receive a proposed decision on this request in late 2024. In February 2024, the CPUC approved an interim cost recovery mechanism that would permit SDG&E to recover in rates $194 million of its wildfire mitigation plan regulatory account balance in 2024 and, if a recovery mechanism is not in place by January 1, 2025, an additional $96 million in 2025. Such recovery of SDG&E’s wildfire mitigation plan regulatory account balance will be subject to reasonableness review. SDG&E also expects to submit a separate request for review and recovery of its 2023 wildfire mitigation plan costs in late 2024.

A CPUC cost of capital proceeding determines a utility’s authorized capital structure and authorized return on rate base. The CCM applies in the interim years between required cost of capital applications and considers changes in the cost of capital based on changes in interest rates based on the applicable utility bond index published by Moody’s (the CCM benchmark rate) for each 12-month period ending September 30 (the measurement period). The index applicable to SDG&E and SoCalGas is based on each utility’s credit rating. The CCM benchmark rate is the basis of comparison to determine if the CCM is triggered in each measurement period, which occurs if the change in the applicable Moody’s utility bond index relative to the CCM benchmark rate is larger than plus or minus 1.000% at the end of the measurement period. The CCM, if triggered, would automatically update the

authorized cost of debt based on actual costs and update the authorized ROE upward or downward by one-half of the difference between the CCM benchmark rate and the applicable Moody’s utility bond index, subject to regulatory approval. Alternatively, each of SDG&E and SoCalGas is permitted to file a cost of capital application to have its cost of capital determined in lieu of the CCM in an interim year in which an extraordinary or catastrophic event materially impacts its cost of capital and affects utilities differently than the market as a whole.


AUTHORIZED COST OF CAPITAL FOR 2020 – 2022

SDG&E							SoCalGas
Authorized weighting		Return on rate base		Weighted return on rate base			Authorized weighting		Return on rate base		Weighted return on rate base
45.25	%	4.59	%	2.08	%	Long-Term Debt	45.60	%	4.23	%	1.93	%
2.75		6.22		0.17		Preferred Equity	2.40		6.00		0.14
52.00		10.20		5.30		Common Equity	52.00		10.05		5.23
100.00	%			7.55	%		100.00	%			7.30	%

The CPUC approved the following cost of capital for SDG&E and SoCalGas that became effective on January 1, 2023 and was to remain in effect through December 31, 2025, subject to the CCM. The CPUC has issued a ruling to initiate a second phase of this cost of capital proceeding to evaluate potential modifications to the CCM.


AUTHORIZED COST OF CAPITAL FOR 2023

SDG&E							SoCalGas
Authorized weighting		Return on rate base		Weighted return on rate base(1)			Authorized weighting		Return on rate base		Weighted return on rate base
45.25	%	4.05	%	1.83	%	Long-Term Debt	45.60	%	4.07	%	1.86	%
2.75		6.22		0.17		Preferred Equity	2.40		6.00		0.14
52.00		9.95		5.17		Common Equity	52.00		9.80		5.10
100.00	%			7.18	%		100.00	%			7.10	%

For the measurement period that ended on September 30, 2023, SDG&E’s CCM benchmark rate was 4.367% based on Moody’s Baa- utility bond index and SoCalGas’ CCM benchmark rate was 4.074% based on Moody’s A- utility bond index. The actual average rate during the measurement period was 5.777% for SDG&E and 5.472% for SoCalGas. As such, the CCM was triggered for SDG&E and SoCalGas on September 30, 2023. In December 2023, the CPUC approved increases to SDG&E’s and SoCalGas’ authorized rates of return effective January 1, 2024, which will remain in effect through December 31, 2025, subject to the CCM. In January 2024, several parties submitted a request for the CPUC to review such approval.


AUTHORIZED COST OF CAPITAL FOR 2024 – 2025

SDG&E							SoCalGas
Authorized weighting		Return on rate base		Weighted return on rate base			Authorized weighting		Return on rate base		Weighted return on rate base
45.25	%	4.34	%	1.96	%	Long-Term Debt	45.60	%	4.54	%	2.07	%
2.75		6.22		0.17		Preferred Equity	2.40		6.00		0.14
52.00		10.65		5.54		Common Equity	52.00		10.50		5.46
100.00	%			7.67	%		100.00	%			7.67	%

SDG&E files separately with the FERC for its authorized ROE on FERC-regulated electric transmission operations and assets. SDG&E’s currently effective TO5 settlement provides for a ROE of 10.60%, consisting of a base ROE of 10.10% plus an additional 50 bps for participation in the California ISO (the California ISO adder). If the FERC issues an order ruling that California IOUs are no longer eligible for the California ISO adder, SDG&E would refund the California ISO adder as of the refund effective date (June 1, 2019) or such other date set by the FERC if such a refund is determined to be required by the terms of the TO5 settlement. The TO5 settlement will remain in effect until terminated by a notice provided at least six months before the end of the calendar year. Following any such notice, SDG&E would file an updated rate request with an effective date of January 1 of the following year.

SDG&E has a 20% ownership interest in SONGS, a nuclear generating facility near San Clemente, California, which permanently ceased operations in June 2013 after an extended outage as a result of issues with the steam generators used in the facility. Edison, the majority owner and operator of SONGS, notified SDG&E that it had reached a decision to permanently retire SONGS and seek approval from the NRC to start the decommissioning activities for the entire facility. SONGS is subject to the jurisdiction of the NRC and the CPUC.

SDG&E, and each of the other owners, holds its undivided interest as a tenant in common in the property. Each owner is responsible for financing its share of costs. SDG&E’s share of operating expenses is included in Sempra’s and SDG&E’s Consolidated Statements of Operations.

As a result of Edison’s decision to permanently retire SONGS Units 2 and 3, Edison began the decommissioning phase of the plant. Major decommissioning work began in 2020. We expect the majority of the decommissioning work to be completed around 2030. Decommissioning of Unit 1, removed from service in 1992, is largely complete. The remaining work for Unit 1 will be completed once Units 2 and 3 are dismantled and the spent fuel is removed from the site. The spent fuel is currently being stored on-site, until the DOE identifies a spent fuel storage facility and puts in place a program for the fuel’s disposal, as we discuss below. SDG&E is responsible for approximately 20% of the total decommissioning cost.

In accordance with state and federal requirements and regulations, SDG&E has assets held in the NDT to fund its share of decommissioning costs for SONGS Units 1, 2 and 3. Amounts that were collected in rates for SONGS’ decommissioning are invested in the NDT, which is comprised of externally managed trust funds. Amounts held by the NDT are invested in accordance with CPUC regulations. SDG&E classifies debt and equity securities held in the NDT as available-for-sale. The NDT assets are presented on the Sempra and SDG&E Consolidated Balance Sheets at fair value with the offsetting credits recorded in noncurrent Regulatory Liabilities.

Except for the use of funds for the planning of decommissioning activities or NDT administrative costs, CPUC approval is required for SDG&E to access the NDT assets to fund SONGS decommissioning costs for Units 2 and 3. In December 2023, the CPUC granted SDG&E authorization to access NDT funds of up to $79 million for forecasted 2024 costs.

In September 2020, the IRS and the U.S. Department of the Treasury published final regulations that clarify the definition of “nuclear decommissioning costs,” which are costs that may be paid for or reimbursed from a qualified trust fund. The final regulations adopted most of the provisions of the proposed regulations issued in December 2016. The final regulations apply to taxable years ending on or after September 4, 2020 and confirm that the definition of “nuclear decommissioning costs” includes amounts related to the storage of spent nuclear fuel at both on-site and off-site ISFSIs.

The final regulations also clarify that costs incurred for ISFSIs that may be or are expected to be reimbursed by the DOE may be paid or reimbursed from a qualified trust fund. Accordingly, the final regulations allow SDG&E the option to access qualified trust funds to recover spent fuel storage costs before Edison reaches final settlement with the DOE regarding the DOE’s reimbursement of these costs. Historically, the DOE’s reimbursements of spent fuel storage costs have not resulted in timely or complete recovery of these costs. We discuss the DOE’s responsibility for spent nuclear fuel below.

The following table shows the fair values and gross unrealized gains and losses for the securities held in the NDT on the Sempra and SDG&E Consolidated Balance Sheets. We provide additional fair value disclosures for the NDT in Note 12.


NUCLEAR DECOMMISSIONING TRUSTS
(Dollars in millions)
	Cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
	December 31, 2023
Short-term investments, primarily cash equivalents	$	21	$	—	$	—	$	21
Equity securities	89		225		(2)		312
Debt securities:
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies(1)	50		2		(1)		51
Municipal bonds(2)	280		3		(8)		275
Other securities(3)	228		3		(11)		220
Total debt securities	558		8		(20)		546
Receivables (payables), net	(7)		—		—		(7)
Total	$	661	$	233	$	(22)	$	872

	December 31, 2022
Short-term investments, primarily cash equivalents	$	11	$	—	$	—	$	11
Equity securities	111		194		(8)		297
Debt securities:
Debt securities issued by the U.S. Treasury and other U.S. government corporations and agencies	40		1		(1)		40
Municipal bonds	283		1		(14)		270
Other securities	248		—		(21)		227
Total debt securities	571		2		(36)		537
Receivables (payables), net	(4)		—		—		(4)
Total	$	689	$	196	$	(44)	$	841


SALES OF SECURITIES IN THE NUCLEAR DECOMMISSIONING TRUSTS
(Dollars in millions)
	Years ended December 31,
	2023		2022		2021
Proceeds from sales	$	592	$	639	$	961
Gross realized gains	27		18		67
Gross realized losses	(14)		(20)		(5)

Net unrealized gains and losses, as well as realized gains and losses that are reinvested in the NDT, are included in noncurrent Regulatory Liabilities on Sempra’s and SDG&E’s Consolidated Balance Sheets. We determine the cost of securities in the trusts on the basis of specific identification.

The present value of SDG&E’s ARO related to decommissioning costs for all three SONGS units was $504 million at December 31, 2023 and is based on a cost study prepared in 2020 that is pending CPUC approval. SDG&E expects to receive a proposed decision in the first half of 2024. The ARO for Units 2 and 3 reflects the acceleration of the start of decommissioning of these units as a result of the early closure of the plant. We expect SDG&E’s undiscounted SONGS decommissioning payments to be $109 million in 2024, $46 million in 2025, $52 million in 2026, $32 million in 2027, $23 million in 2028, and $663 million thereafter.

Spent nuclear fuel from SONGS is currently stored on-site in an ISFSI licensed by the NRC. The ISFSI will operate until 2051, when it is assumed that the DOE will have taken custody of all the SONGS spent fuel. The ISFSI would then be decommissioned, and the site restored to its original environmental state. Until then, SONGS owners are responsible for interim storage of spent nuclear fuel at SONGS.

The Nuclear Waste Policy Act of 1982 made the DOE responsible for accepting, transporting, and disposing of spent nuclear fuel. However, it is uncertain when the DOE will begin accepting spent nuclear fuel from SONGS. This delay will lead to increased costs for spent fuel storage. In November 2019, Edison filed a claim for spent fuel management costs in the U.S. Court of Federal Claims for the time period from January 2017 through July 2018, which is pending DOE approval. It is unclear when Edison will pursue litigation claims for spent fuel management costs incurred on or after August 1, 2018. SDG&E will continue to support Edison in its pursuit of claims on behalf of the SONGS co-owners against the DOE for its failure to timely accept the spent nuclear fuel.

SDG&E and the other owners of SONGS have insurance to cover claims from nuclear liability incidents arising at SONGS. Currently, this insurance provides $450 million in coverage limits, the maximum amount available, including coverage for acts of terrorism. In addition, the Price-Anderson Act provides an additional $110 million of coverage. If a nuclear liability loss occurs at SONGS and exceeds the $450 million insurance limit, this additional coverage would be available to provide a total of $560 million in coverage limits per incident.

The SONGS owners have nuclear property damage insurance of $130 million, which exceeds the minimum federal requirement of $50 million. This insurance coverage is provided through NEIL. The NEIL policies have specific exclusions and limitations that can result in reduced coverage. Insured members as a group are subject to retrospective premium assessments to cover losses sustained by NEIL under all issued policies. SDG&E could be assessed up to $2 million of retrospective premiums based on overall member claims.

The nuclear property insurance program includes an industry aggregate loss limit for non-certified acts of terrorism (as defined by the Terrorism Risk Insurance Act) of $3.24 billion. This is the maximum amount that will be paid to insured members who suffer losses or damages from these non-certified terrorist acts.