XML 95 R53.htm IDEA: XBRL DOCUMENT
v3.24.0.1

REGULATORY MATTERS | 12 Months Ended
--- | ---
Dec. 31, 2023
Regulated Operations [Abstract] |
REGULATORY MATTERS | REGULATORY MATTERS Regulatory Assets and Liabilities Details of regulatory assets and (liabilities) reflected in the balance sheets at December 31, 2023 and 2022 are provided in the following tables:
| Southern Company | Alabama Power | Georgia Power | Mississippi Power | Southern Company Gas
| (in millions)
At December 31, 2023 |  |  |  |  |
AROs(a)(w) | $ | 5,733 |  | $ | 1,936 |  | $ | 3,505 |  | $ | 247 |  | $ | — |
Retiree benefit plans(b)(w) | 3,011 |  | 815 |  | 976 |  | 140 |  | 146 |
Remaining net book value of retired assets(c) | 1,357 |  | 499 |  | 841 |  | 17 |  | — |
Deferred income tax charges(d) | 897 |  | 262 |  | 605 |  | 28 |  | — |
Under recovered regulatory clause revenues(e) | 413 |  | 381 |  | — |  | 12 |  | 20 |
Fuel-hedging (realized and unrealized) losses(f) | 270 |  | 100 |  | 121 |  | 49 |  | — |
Deferred depreciation(g) | 270 |  | 143 |  | 127 |  | — |  | — |
Environmental remediation(h)(w) | 255 |  | — |  | 20 |  | — |  | 235 |
Loss on reacquired debt(i) | 238 |  | 35 |  | 197 |  | 5 |  | 1 |
Vacation pay(j)(w) | 217 |  | 83 |  | 107 |  | 11 |  | 16 |
Software and cloud computing costs(k) | 150 |  | 59 |  | 84 |  | 2 |  | 5 |
Regulatory clauses(l) | 140 |  | 112 |  | — |  | — |  | 28 |
Storm damage(m) | 92 |  | — |  | 54 |  | 38 |  | — |
Nuclear outage(n) | 83 |  | 50 |  | 33 |  | — |  | — |
Long-term debt fair value adjustment(o) | 60 |  | — |  | — |  | — |  | 60 |
Qualifying repairs of natural gas distribution systems(p) | 40 |  | — |  | — |  | — |  | 40 |
Plant Daniel Units 3 and 4(q) | 25 |  | — |  | — |  | 25 |  | — |
Kemper County energy facility assets, net(r) | 7 |  | — |  | — |  | 7 |  | — |
Other regulatory assets(s) | 182 |  | 39 |  | 33 |  | 18 |  | 93 |
Deferred income tax credits(d) | (4,686) |  | (1,506) |  | (2,161) |  | (241) |  | (759) |
Other cost of removal obligations(a) | (1,312) |  | 28 |  | 617 |  | (186) |  | (1,771) |
Over recovered regulatory clause revenues(e) | (287) |  | (3) |  | (46) |  | — |  | (238) |
Reliability reserves(t) | (179) |  | (143) |  | — |  | (36) |  | — |
Storm/property damage reserves(t) | (120) |  | (76) |  | — |  | (44) |  | — |
Customer refunds(u) | (19) |  | (15) |  | (4) |  | — |  | — |
Fuel-hedging (realized and unrealized) gains(f) | (6) |  | (5) |  | (1) |  |  | — |
Other regulatory liabilities(v) | (308) |  | (74) |  | (18) |  | (2) |  | (101) |
Total regulatory assets (liabilities), net | $ | 6,523 |  | $ | 2,720 |  | $ | 5,090 |  | $ | 90 |  | $ | (2,225) |
| Southern Company | Alabama Power | Georgia Power | Mississippi Power | Southern Company Gas
| (in millions)
At December 31, 2022 |  |  |  |  |
AROs(a)(w) | $ | 6,096 |  | $ | 1,971 |  | $ | 3,829 |  | $ | 242 |  | $ | — |
Retiree benefit plans(b)(w) | 2,517 |  | 675 |  | 848 |  | 113 |  | 114 |
Remaining net book value of retired assets(c) | 1,543 |  | 562 |  | 962 |  | 19 |  | — |
Under recovered regulatory clause revenues(e) | 953 |  | 788 |  | — |  | 31 |  | 134 |
Deferred income tax charges(d) | 866 |  | 250 |  | 583 |  | 30 |  | — |
Environmental remediation(h)(w) | 294 |  | — |  | 25 |  | — |  | 269 |
Loss on reacquired debt(i) | 257 |  | 38 |  | 213 |  | 5 |  | 1 |
Vacation pay(j)(w) | 212 |  | 82 |  | 108 |  | 10 |  | 12 |
Regulatory clauses(l) | 142 |  | 142 |  | — |  | — |  | — |
Software and cloud computing costs(k) | 111 |  | 46 |  | 59 |  | — |  | 6 |
Nuclear outage(n) | 82 |  | 52 |  | 30 |  | — |  | — |
Long-term debt fair value adjustment(o) | 69 |  | — |  | — |  | — |  | 69 |
Fuel-hedging (realized and unrealized) losses(f) | 60 |  | 15 |  | 45 |  | — |  | — |
Storm damage(m) | 44 |  | — |  | — |  | 44 |  | — |
Plant Daniel Units 3 and 4(q) | 27 |  | — |  | — |  | 27 |  | — |
Qualifying repairs of natural gas distribution systems(p) | 26 |  | — |  | — |  | — |  | 26 |
Kemper County energy facility assets, net(r) | 20 |  | — |  | — |  | 20 |  | — |
Other regulatory assets(s) | 171 |  | 36 |  | 27 |  | 16 |  | 92 |
Deferred income tax credits(d) | (5,251) |  | (1,925) |  | (2,244) |  | (269) |  | (788) |
Other cost of removal obligations(a) | (1,430) |  | 11 |  | 462 |  | (196) |  | (1,707) |
Storm/property damage reserves(t) | (216) |  | (97) |  | (83) |  | (36) |  | — |
Reliability reserves(t) | (191) |  | (166) |  | — |  | (25) |  | — |
Customer refunds(u) | (183) |  | (62) |  | (121) |  | — |  | — |
Fuel-hedging (realized and unrealized) gains(f) | (83) |  | (38) |  | (21) |  | (24) |  | — |
Over recovered regulatory clause revenues(e) | (64) |  | — |  | (38) |  | — |  | (26) |
Other regulatory liabilities(v) | (239) |  | (40) |  | (21) |  | (3) |  | (93) |
Total regulatory assets (liabilities), net | $ | 5,833 |  | $ | 2,340 |  | $ | 4,663 |  | $ | 4 |  | $ | (1,891) |
Unless otherwise noted, the following recovery and amortization periods for these regulatory assets and (liabilities) have been approved by the respective state PSC or regulatory agency: (a)AROs and other cost of removal obligations generally are recorded over the related property lives, which may range up to 64 years for Alabama Power, 56 years for Georgia Power, 55 years for Mississippi Power, and 85 years for Southern Company Gas. AROs and cost of removal obligations are settled and trued up following completion of the related activities. Alabama Power is recovering CCR ARO expenditures over a 38-year period ending in 2054 through Rate CNP Compliance. Effective January 1, 2023, Georgia Power is recovering CCR ARO expenditures over four-year periods through its ECCR tariff. Prior to 2023, expenditures were recovered over three-year periods. See "Georgia Power – Rate Plans" herein and Note 6 for additional information. (b)Recovered and amortized over the average remaining service period, which may range up to 13 years for Alabama Power and Mississippi Power and up to 14 years for Georgia Power and Southern Company Gas. Southern Company's balances also include amounts at SCS and Southern Nuclear that are allocated to the applicable regulated utilities. See Note 11 for additional information. (c)Alabama Power: Primarily represents the net book value of Plant Gorgas Unit 10 ($451 million at December 31, 2023) being amortized over 14 years (through 2037) and Plant Barry Unit 4 ($39 million at December 31, 2023) being amortized over 11 years (through 2034). See "Alabama Power – Environmental Accounting Order" herein for additional information. Georgia Power: Net book values of Plant Wansley Units 1 and 2, Plant Hammond Units 1 through 4, and Plant Branch Unit 4 (totaling $488 million, $339 million, and $8 million, respectively, at December 31, 2023) are being amortized over remaining periods between one and 12 years (between 2024 and 2035). Balance also includes unusable materials and supplies inventories, for which the Georgia PSC will determine a recovery period in a future base rate case. Mississippi Power: Represents net book value of certain environmental compliance assets at Plant Watson and Plant Greene County. The retail portion is being amortized over a 10-year period through 2030 and the wholesale portion is being amortized over a 14-year period through 2035. See "Mississippi Power – Environmental Compliance Overview Plan" herein for additional information. (d)Deferred income tax charges are recovered and deferred income tax credits are primarily amortized over the related property lives, which may range up to 64 years for Alabama Power, 56 years for Georgia Power, 55 years for Mississippi Power, and 85 years for Southern Company Gas. See Note 10 for additional information. As a result of the Tax Reform Legislation, these accounts include certain deferred income tax assets and liabilities not subject to normalization, as described further below: Alabama Power: Related amounts at December 31, 2023 include excess federal deferred income tax liabilities that are available for the benefit of customers in 2024 and/or 2025, as discussed under "Alabama Power – Excess Accumulated Deferred Income Tax Accounting Order" herein. Remaining amounts are being recovered and amortized ratably over the related property lives. Georgia Power: Related amounts include $145 million of deferred income tax assets related to construction costs for Plant Vogtle Units 3 and 4 to be recovered over a 10-year period beginning the month after Unit 4 achieves commercial operation. See "Georgia Power – Nuclear Construction – Regulatory Matters" herein for additional information on recovery of costs related to Plant Vogtle Units 3 and 4. Mississippi Power: Related amounts include retail deferred income tax liabilities ($11 million at December 31, 2023) that are expected to be fully amortized through 2024. Southern Company Gas: Related amounts include deferred income tax liabilities ($1 million at December 31, 2023) being amortized through 2024. See "Southern Company Gas – Rate Proceedings" herein for additional information. (e)Alabama Power: Balances are recorded monthly and expected to be recovered over periods of up to seven years, with the majority expected to be recovered within one year. See "Alabama Power – Rate CNP PPA," " – Rate CNP Compliance," and " – Rate ECR" herein for additional information. Georgia Power: Balances are recorded monthly and expected to be recovered or returned within two years. See "Georgia Power – Rate Plans" herein for additional information. Mississippi Power: At December 31, 2023, $12 million is expected to be recovered through various rate recovery mechanisms over a period to be determined in future rate filings. See "Mississippi Power – Ad Valorem Tax Adjustment" herein for additional information. Southern Company Gas: Balances are recorded and recovered or amortized over periods generally not exceeding five years. In addition to natural gas cost recovery mechanisms, the natural gas distribution utilities have various other cost recovery mechanisms for the recovery of costs, including those related to infrastructure replacement programs. (f)Fuel-hedging assets and liabilities are recorded over the life of the underlying hedged purchase contracts. Upon final settlement, actual costs incurred are recovered through the applicable traditional electric operating company's fuel cost recovery mechanism. Purchase contracts generally do not exceed three and a half years for Alabama Power, three years for Georgia Power, and four years for Mississippi Power. (g)Alabama Power: Represents deferred depreciation expense for Plant Barry Unit 5 ($57 million at December 31, 2023) and Plant Barry common coal assets ($24 million at December 31, 2023) to be amortized until 2036 beginning when Plant Barry Unit 5 is retired and Plant Gaston Unit 5 coal assets ($62 million at December 31, 2023) to be amortized until 2039 beginning when the assets are retired. Georgia Power: Represents deferred depreciation expense for Plant Scherer Units 1 through 3 ($70 million at December 31, 2023) to be amortized over six years beginning in 2029 and Plant Bowen Units 1 and 2 ($40 million at December 31, 2023) to be amortized over four years beginning in 2031, both as approved under Georgia Power's 2022 ARP, and Plant Vogtle Unit 3 and common facilities ($17 million at December 31, 2023) to be amortized over a 10-year period beginning the month after Plant Vogtle Unit 4 achieves commercial operation. See "Georgia Power – Nuclear Construction – Regulatory Matters" herein for additional information on recovery of costs related to Plant Vogtle Units 3 and 4. (h)Effective January 1, 2023, Georgia Power is recovering $5 million annually for environmental remediation under the 2022 ARP. Southern Company Gas' costs are recovered through environmental cost recovery mechanisms when the remediation work is performed. See Note 3 under "Environmental Remediation" for additional information. (i)Recovered over either the remaining life of the original issue or, if refinanced, over the remaining life of the new issue. At December 31, 2023, the remaining amortization periods do not exceed 24 years for Alabama Power, 29 years for Georgia Power, 18 years for Mississippi Power, and four years for Southern Company Gas. (j)Recorded as earned by employees and recovered as paid, generally within one year. Includes both vacation and banked holiday pay, if applicable. (k)Represents certain deferred operations and maintenance costs associated with software and cloud computing projects. For Alabama Power, costs are amortized ratably over the life of the related software, which ranges up to 10 years (through 2034). See "Alabama Power – Software Accounting Order" herein for additional information. For Georgia Power, costs incurred through 2022 are being amortized over five years (through 2027) and the recovery period for costs incurred after 2022 will be determined in its next base rate case. For Mississippi Power, the recovery period will be determined in Mississippi Power's annual PEP filing process. For Southern Company Gas, costs are being amortized ratably over the life of the related software, which ranges up to 10 years (through 2034). (l)Alabama Power: Effective January 1, 2023, balance is being amortized through Rate RSE over a five-year period ending in 2027. Southern Company Gas: Represents amounts related to Nicor Gas' volume balancing adjustment rider expected to be recovered over a period of less than two years. (m)See "Georgia Power – Storm Damage Recovery" herein and Note 1 under "Storm Damage and Reliability Reserves" for additional information. Mississippi Power's balance represents deferred storm costs associated with Hurricanes Ida and Zeta being recovered through PEP over a seven-year period through 2029. (n)Nuclear outage costs are deferred to a regulatory asset when incurred and amortized over a subsequent period of 18 months for Alabama Power and up to 24 months for Georgia Power. See Note 5 for additional information. (o)Recovered over the remaining lives of the original debt issuances at acquisition, which range up to 15 years at December 31, 2023. (p)Represents deferred costs of certain repairs at Atlanta Gas Light being amortized over 20 years. (q)Represents the difference between Mississippi Power's revenue requirement for Plant Daniel Units 3 and 4 under purchase accounting and operating lease accounting. At December 31, 2023, consists of the $17 million retail portion being amortized through 2039 over the remaining life of the related property and the $8 million wholesale portion being amortized through 2035. (r)At December 31, 2023, includes $9 million of regulatory assets (wholesale) expected to be fully amortized by 2035 and $2 million of regulatory liabilities (retail) expected to be fully amortized by 2024. (s)Comprised of numerous immaterial components with remaining amortization periods at December 31, 2023 generally not exceeding 20 years for Alabama Power, 10 years for Georgia Power, 14 years for Mississippi Power, and 15 years for Southern Company Gas. (t)Utilized as related expenses are incurred. See "Alabama Power – Rate NDR" and " – Reliability Reserve Accounting Order," "Georgia Power – Storm Damage Recovery," and "Mississippi Power – System Restoration Rider" and " – Reliability Reserve Accounting Order" herein and Note 1 under "Storm Damage and Reliability Reserves" for additional information. (u)Primarily includes approximately $15 million and $62 million at December 31, 2023 and 2022, respectively, for Alabama Power and $119 million at December 31, 2022 for Georgia Power as a result of each company exceeding its allowed retail return range. Georgia Power's balances also include immaterial amounts related to refunds for transmission service customers. See "Alabama Power – Rate RSE" and "Georgia Power – Rate Plans" herein for additional information. (v)Comprised of numerous immaterial components with remaining amortization periods at December 31, 2023 generally not exceeding 11 years for Alabama Power, nine years for Georgia Power, four years for Mississippi Power, and 20 years for Southern Company Gas. (w)Generally not earning a return as they are excluded from rate base or are offset in rate base by a corresponding asset or liability. Alabama Power Alabama Power's revenues from regulated retail operations are collected through various rate mechanisms subject to the oversight of the Alabama PSC. Alabama Power currently recovers its costs from the regulated retail business primarily through Rate RSE, Rate CNP, Rate ECR, and Rate NDR. In addition, the Alabama PSC issues accounting orders to address current events impacting Alabama Power. Renewable Generation Certificate Through the issuance of a Renewable Generation Certificate (RGC), Alabama Power is authorized by the Alabama PSC to procure renewable capacity and energy and to market the related energy and environmental attributes to customers and other third parties. On April 4, 2023, the Alabama PSC approved two new solar PPAs totaling 160 MWs. Upon approval of these PPAs, Alabama Power had procured solar capacity totaling approximately 490 MWs under the RGC's original 500-MW limit. On June 14, 2023, the Alabama PSC issued an order approving modifications to Alabama Power's RGC. The modifications authorized Alabama Power to procure an additional 2,400 MWs of renewable capacity and energy by June 14, 2029 and to market the related energy and environmental attributes to customers and other third parties. The modifications also increased the size of allowable renewable projects from 80 MWs to 200 MWs and increased the annual approval limit from 160 MWs to 400 MWs. Rate RSE The Alabama PSC has adopted Rate RSE that provides for periodic annual adjustments based upon Alabama Power's projected weighted common equity return (WCER) compared to an allowable range. Rate RSE adjustments are based on forward-looking information for the applicable upcoming calendar year. Rate RSE adjustments for any two-year period, when averaged together, cannot exceed 4.0% and any annual adjustment is limited to 5.0%. When the projected WCER is under the allowed range, there is an adjusting point of 5.98% and eligibility for a performance-based adder of seven basis points, or 0.07%, to the WCER adjusting point if Alabama Power (i) has an "A" credit rating equivalent with at least one of the recognized rating agencies or (ii) is in the top one-third of a designated customer value benchmark survey. Alabama Power continues to reduce growth in total debt by increasing equity, with corresponding reductions in debt issuances, thereby de-leveraging its capital structure. Alabama Power's goal is to achieve an equity ratio of approximately 55% by the end of 2025. At December 31, 2023 and 2022, Alabama Power's equity ratio was approximately 52.3% and 52.2%, respectively. Generally, during a year without a Rate RSE upward adjustment, if Alabama Power's actual WCER is between 6.15% and 7.65%, customers will receive 25% of the amount between 6.15% and 6.65%, 40% of the amount between 6.65% and 7.15%, and 75% of the amount between 7.15% and 7.65%. Customers will receive all amounts in excess of an actual WCER of 7.65%. During a year with a Rate RSE upward adjustment, if Alabama Power's actual WCER exceeds 6.15%, customers receive 50% of the amount between 6.15% and 6.90% and all amounts in excess of an actual WCER of 6.90%. Alabama Power's ability to retain a portion of the revenue that causes the actual WCER for a given year to exceed the allowed range positions Alabama Power to address the pressure on its credit quality, without increasing retail rates under Rate RSE in the near term. There is no provision for additional customer billings should the actual retail return fall below the WCER range. Retail rates under Rate RSE did not change for 2022 or 2023. For the years ended December 31, 2021, 2022, and 2023, Alabama Power's WCER exceeded 6.15%, resulting in Alabama Power establishing a current regulatory liability of $181 million, $62 million, and $15 million, respectively, for Rate RSE refunds. In accordance with an Alabama PSC order issued in February 2022, Alabama Power applied $126 million of the 2021 refund to reduce the Rate ECR under recovered balance and the remaining $55 million was refunded to customers through bill credits in July 2022. In accordance with an Alabama PSC order issued on February 7, 2023, Alabama Power refunded the 2022 amount to customers through bill credits in August 2023. The $15 million regulatory liability at December 31, 2023 will be refunded to customers through bill credits in April 2024. On December 1, 2023, Alabama Power made its required annual Rate RSE submission to the Alabama PSC of projected data for calendar year 2024. Projected earnings were within the specified range; therefore, retail rates under Rate RSE remain unchanged for 2024. Excess Accumulated Deferred Income Tax Accounting Order In December 2022, the Alabama PSC directed Alabama Power to accelerate the amortization of a regulatory liability associated with excess federal accumulated deferred income taxes. Under this order, in 2023, approximately $304 million was returned to customers through bill credits to offset the impact of the rate increase discussed under "Rate CNP Depreciation" herein. On October 3, 2023, the Alabama PSC issued an order modifying its December 2022 order and authorizing Alabama Power to (i) flow back in 2023 approximately $24 million of certain federal excess accumulated deferred income taxes resulting from the Tax Cuts and Jobs Act of 2017 and (ii) make available any remaining balance of excess accumulated deferred income taxes at the end of 2023 for the benefit of customers in 2024 and/or 2025. At December 31, 2023, the remaining balance was $81 million, of which approximately $67 million and $14 million will flow back in 2024 and 2025, respectively, for the benefit of customers. Rate CNP New Plant Rate CNP New Plant allows for recovery of Alabama Power's retail costs associated with newly developed or acquired certificated generating facilities placed into retail service. No adjustments to Rate CNP New Plant occurred during the period January 2021 through October 2022. In July 2022, the Alabama PSC approved a CCN authorizing Alabama Power to complete the acquisition of the Calhoun Generating Station. The transaction closed in September 2022 and, in October 2022, Alabama Power filed Rate CNP New Plant with the Alabama PSC to recover the related costs. The filing reflected an increase in annual revenues of $34 million, or 0.6%, effective with November 2022 billings. In 2020, the Alabama PSC approved a CCN authorizing Alabama Power to complete the acquisition of the Central Alabama Generating Station, which occurred in August 2020. Through May 2023, Alabama Power recovered substantially all costs associated with the Central Alabama Generating Station through Rate RSE, offset by revenues from a power sales agreement. Beginning in July 2022, fuel costs associated with Central Alabama Generating Station are being recovered through Rate ECR. On March 24, 2023, Alabama Power filed Rate CNP New Plant with the Alabama PSC to recover costs associated with the acquisition of the Central Alabama Generating Station. The filing reflected an annual increase in retail revenues of $78 million, or 1.1%, effective with June 2023 billings. On May 24, 2023, the Central Alabama Generating Station was placed into retail service. The Alabama PSC's 2020 CCN also authorized Alabama Power to construct an approximately 720-MW combined cycle facility at Alabama Power's Plant Barry (Plant Barry Unit 8) and the recovery of estimated in-service costs. On November 1, 2023, the unit was placed in service. On December 1, 2023, Alabama Power filed Rate CNP New Plant with the Alabama PSC to recover the related costs. The filing reflected an annual increase in retail revenues of $91 million, or 1.4%, effective with January 2024 billings. Rate CNP PPA Rate CNP PPA allows for the recovery of Alabama Power's retail costs associated with certificated PPAs. Revenues for Rate CNP PPA, as recorded on the financial statements, are adjusted for differences in actual recoverable costs and amounts billed in current regulated rates. Accordingly, changes in the billing factors will have no significant effect on Southern Company's or Alabama Power's revenues or net income but will affect annual cash flow. No adjustments to Rate CNP PPA occurred during the period 2021 through 2023 and no adjustment is expected for 2024. At December 31, 2023 and 2022, Alabama Power had an under recovered Rate CNP PPA balance of $103 million and $120 million, respectively, of which $18 million and $18 million, respectively, is included in other regulatory assets, current and $85 million and $102 million, respectively, is included in other regulatory assets, deferred on the balance sheet. Rate CNP Compliance Rate CNP Compliance allows for the recovery of Alabama Power's retail costs associated with laws, regulations, and other such mandates directed at the utility industry involving the environment, security, reliability, safety, sustainability, or similar considerations impacting Alabama Power's facilities or operations. Rate CNP Compliance is based on forward-looking information and provides for the recovery of these costs pursuant to factors that are calculated and submitted to the Alabama PSC by December 1 with rates effective for the following calendar year. Compliance costs to be recovered include operations and maintenance expenses, depreciation, and a return on certain invested capital. Revenues for Rate CNP Compliance, as recorded on the financial statements, are adjusted for differences in actual recoverable costs and amounts billed in current regulated rates. Accordingly, changes in the billing factors will have no significant effect on Southern Company's or Alabama Power's revenues or net income, but will affect annual cash flow. Changes in Rate CNP Compliance-related operations and maintenance expenses and depreciation generally will have no effect on net income. In November 2021, December 2022, and December 2023, Alabama Power submitted calculations to the Alabama PSC associated with its cost of complying with governmental mandates for the following calendar year, as provided under Rate CNP Compliance. The 2021 filing reflected a projected under recovered retail revenue requirement of approximately $59 million. In December 2021, the Alabama PSC issued a consent order that Alabama Power leave the 2021 Rate CNP Compliance factors in effect for 2022, with any prior year under collected amount deemed recovered before any current year amounts are recovered and any remaining under recovery reflected in the 2022 filing. The 2022 filing reflected a $255 million, or 3.7%, annual increase effective with January 2023 billings, primarily due to updated depreciation rates. The 2023 filing reflected a $23 million, or 0.3%, annual decrease effective with January 2024 billings. At December 31, 2023, Alabama Power had an under recovered Rate CNP Compliance balance of $33 million, of which $8 million is included in other regulatory assets, current and $25 million is included in other regulatory assets, deferred on the balances sheet, compared to an under recovered balance at December 31, 2022 of $47 million included in other regulatory assets, current on the balance sheet. Rate CNP Depreciation In December 2022, the Alabama PSC approved Rate CNP Depreciation, which allows Alabama Power to recover changes in depreciation resulting from updates to certain depreciation rates, excluding any depreciation recovered through Rate CNP New Plant, Rate CNP Compliance, or costs associated with the capitalization of asset retirement costs. Rate CNP Depreciation resulted in an annual revenue increase of approximately $318 million, or 4.6%, effective with January 2023 billings. See "Excess Accumulated Deferred Income Tax Accounting Order" herein for information related to 2023 customer bill credits approved by the Alabama PSC. Rate ECR Rate ECR recovers Alabama Power's retail energy costs based on an estimate of future energy costs and the current over or under recovered balance. Revenues recognized under Rate ECR and recorded on the financial statements are adjusted for the difference in actual recoverable fuel costs and amounts billed in current regulated rates. The difference in the recoverable fuel costs and amounts billed gives rise to the over or under recovered amounts recorded as regulatory assets or liabilities. Alabama Power, along with the Alabama PSC, continually monitors the over or under recovered cost balance to determine whether an adjustment to billing rates is required. Changes in the Rate ECR factor have no significant effect on Southern Company's or Alabama Power's net income but will impact the related operating cash flows. The Alabama PSC may approve billing rates under Rate ECR of up to 5.910 cents per KWH. The Alabama PSC approved adjustments to Rate ECR from 1.960 cents per KWH to 2.557 cents per KWH, or approximately $310 million annually, effective with August 2022 billings and from 2.557 cents per KWH to 3.510 cents per KWH, or approximately $500 million annually, effective with December 2022 billings. On November 9, 2023, the Alabama PSC approved a decrease to Rate ECR from 3.510 cents per KWH to 3.270 cents per KWH, or approximately $126 million annually, effective with December 2023 billings. The rate will adjust to 5.910 cents per KWH in January 2025 absent a further order from the Alabama PSC. At December 31, 2023 and 2022, Alabama Power's under recovered fuel costs totaled $246 million and $622 million, respectively, of which $246 million and $102 million, respectively, is included in regulatory assets – under recovered retail fuel clause revenues and $520 million of the December 31, 2022 balance is included in other regulatory assets, deferred on the balance sheets. These classifications are based on estimates, which include such factors as weather, generation availability, energy demand, and the price of energy. A change in any of these factors could have a significant impact on the timing of any recovery or return of fuel costs. Software Accounting Order The Alabama PSC authorizes Alabama Power to establish a regulatory asset for operations and maintenance costs associated with software implementation projects. The regulatory asset is amortized ratably over the life of the related software. At December 31, 2023 and 2022, the regulatory asset balance totaled $59 million and $46 million, respectively, and is included in other regulatory assets, deferred on the balance sheet. Plant Greene County Alabama Power jointly owns Plant Greene County with an affiliate, Mississippi Power. See Note 5 under "Joint Ownership Agreements" for additional information. In 2021, the Mississippi PSC concluded its review of Mississippi Power's 2021 IRP, which included a schedule to retire Mississippi Power's 40% ownership interest in Plant Greene County Units 1 and 2 in December 2025 and 2026, respectively, consistent with each unit's remaining useful life. Alabama Power and Mississippi Power have continued to evaluate operating conditions and business needs relevant to the anticipated retirement of Plant Greene County and now expect the units to remain in service beyond the previously indicated dates. The Plant Greene County unit retirements require the completion by Alabama Power of transmission and system reliability improvements, as well as agreement by Alabama Power. The ultimate outcome of this matter cannot be determined at this time. See "Mississippi Power – Integrated Resource Plan" herein for additional information. Rate NDR Based on an order from the Alabama PSC, Alabama Power maintains a reserve for operations and maintenance expenses to cover the cost of damages from major storms to its transmission and distribution facilities. The order approves a separate monthly Rate NDR charge to customers consisting of two components. The first component is intended to establish and maintain a reserve balance for future storms and is an on-going part of customer billing. When the reserve balance falls below $50 million, a reserve establishment charge will be activated (and the on-going reserve maintenance charge concurrently suspended) until the reserve balance reaches $75 million. The second component of the Rate NDR charge is intended to allow recovery of any existing deferred storm-related operations and maintenance costs and any future reserve deficits over a 48-month period (24-month period prior to modifications approved by the Alabama PSC in July 2022). The Alabama PSC order gives Alabama Power authority to record a deficit balance in the NDR when costs of storm damage exceed any established reserve balance. The maximum total Rate NDR charge was limited to $10.00 per month per non-residential customer account and $5.00 per month per residential customer account through July 12, 2022. Subsequently, modifications approved by the Alabama PSC replaced the maximum total Rate NDR charge with a maximum charge to recover a deficit of $5 per month per non-residential customer account and $2.50 per month per residential customer account. Alabama Power has the authority, based on an order from the Alabama PSC, to accrue certain additional amounts as circumstances warrant, which can be used to offset storm charges. Alabama Power made an additional accrual of $65 million in 2021. Alabama Power collected approximately $12 million, $14 million, and $6 million in 2023, 2022, and 2021, respectively, under Rate NDR. Beginning with August 2022 billings, the reserve establishment charge was suspended and the reserve maintenance charge was activated as a result of the NDR balance exceeding $75 million. Alabama Power expects to collect approximately $12 million annually under Rate NDR unless the NDR balance falls below $50 million. At December 31, 2023 and 2022, the NDR balance was $76 million and $97 million, respectively, and is included in other regulatory liabilities, deferred on the balance sheets. As revenue from the Rate NDR charge is recognized, an equal amount of operations and maintenance expenses related to the NDR will also be recognized. As a result, the Rate NDR charge will not have an effect on net income but will impact operating cash flows. Reliability Reserve Accounting Order In July 2022, the Alabama PSC approved an accounting order authorizing Alabama Power to create a reliability reserve separate from the NDR and transition the previous Rate NDR authority related to reliability expenditures to the reliability reserve. Alabama Power may make accruals to the reliability reserve if the NDR balance exceeds $35 million. At December 31, 2023 and 2022, Alabama Power accrued $52 million and $166 million, respectively, to the reserve. On July 11, 2023, the Alabama PSC issued an order authorizing Alabama Power to expand the existing authority of its reliability reserve to include certain production-related expenses that are intended to maintain reliability in between scheduled generating unit maintenance outages. On August 18, 2023, Alabama Power notified the Alabama PSC of its intent to use a portion of its reliability reserve balance in 2023. During the fourth quarter 2023, Alabama Power used $75 million of the reliability reserve for reliability-related transmission, distribution, and generation expenses and nuclear production-related expenses. At December 31, 2023 and 2022, Alabama Power's reliability reserve balance was $143 million and $166 million, respectively, and is included in other regulatory liabilities, deferred on the balance sheets. Environmental Accounting Order Based on an order from the Alabama PSC (Environmental Accounting Order), Alabama Power is authorized to establish a regulatory asset to record the unrecovered investment costs, including the unrecovered plant asset balance and the unrecovered costs associated with site removal and closure associated with future unit retirements caused by environmental regulations. The regulatory asset is amortized and recovered over the affected unit's remaining useful life, as established prior to the decision regarding early retirement, through Rate CNP Compliance. With the completion of the Calhoun Generating Station acquisition, Alabama Power expected to retire Plant Barry Unit 5 in late 2023 or early 2024, subject to certain operating conditions. In September 2022, Alabama Power reclassified approximately $600 million for Plant Barry Unit 5 from plant in service, net of depreciation to other utility plant, net and will continue to depreciate the asset according to the original depreciation rates. Alabama Power has continued to evaluate operating conditions relevant to the expected retirement of Plant Barry Unit 5 and now expects to retire the unit on or before December 31, 2028. At retirement, Alabama Power will reclassify the remaining net investment costs of the unit to a regulatory asset to be recovered over the unit's remaining useful life, as established prior to the decision to retire, through Rate CNP Compliance. See "Rate CNP New Plant" herein for additional information. In December 2022, in conjunction with Alabama Power's compliance plan for the EPA's final steam electric ELG reconsideration rule, Plant Barry Unit 4 ceased using coal and began operating solely on natural gas. As a result, approximately $42 million of plant in service, net of depreciation was reclassified to a regulatory asset to be recovered through Rate CNP Compliance through 2034, the unit's remaining useful life. Georgia Power Georgia Power's revenues from regulated retail operations are collected through various rate mechanisms subject to the oversight of the Georgia PSC. Georgia Power recovers its costs from the regulated retail business through traditional base tariffs, Demand-Side Management (DSM) tariffs, the ECCR tariff, and Municipal Franchise Fee (MFF) tariffs. These tariffs were set under the 2019 ARP for the years 2020 through 2022 and under the 2022 ARP for the years 2023 through 2025 as described herein. In addition, fuel costs are collected through a separate fuel cost recovery tariff. See "Nuclear Construction – Regulatory Matters" herein for information regarding the approved recovery through retail base rates of certain costs related to Plant Vogtle Unit 3 and the common facilities shared between Plant Vogtle Units 3 and 4 (Common Facilities) that became effective August 1, 2023 based on the in-service date of July 31, 2023 for Unit 3, as well as the base rate adjustments that will occur the first day of the month after Unit 4 achieves commercial operation. Financing costs on certified construction costs of Plant Vogtle Units 3 and 4 that are not included in rate base are being collected through Georgia Power's NCCR tariff. When the base rate adjustments occur following commercial operation of Unit 4, the NCCR tariff will cease to be collected and financing costs will be included in Georgia Power's general retail revenue requirements. See "Nuclear Construction" herein for additional information on Plant Vogtle Units 3 and 4. Rate Plans 2022 ARP In December 2022, the Georgia PSC voted to approve the 2022 ARP, under which Georgia Power increased its rates on January 1, 2023. On November 16, 2023, the Georgia PSC approved tariff adjustments effective January 1, 2024. Details of tariff adjustments are provided in the following table:
Tariff | 2023 |  | 2024 |  |
| (in millions)
Traditional base | $ | 194 |  |  | $ | 275 |  |  |
ECCR | (21) |  |  | (99) |  |  |
DSM | 37 |  |  | 10 |  |  |
MFF | 6 |  |  | 5 |  |  |
Total | $ | 216 |  |  | $ | 191 |  |  |
Under the 2022 ARP, Georgia Power will adjust traditional base, ECCR, DSM, and MFF rates effective January 1, 2025, with the incremental revenue requirements related to DSM tariffs and CCR AROs subject to updates through annual compliance filings to be made at least 90 days prior to the effective date. In the 2022 ARP, the Georgia PSC approved recovery through the ECCR tariff of estimated CCR ARO compliance costs for 2023, 2024, and 2025 over four-year periods beginning January 1 of each respective year, with recovery of construction contingency beginning in the year following actual expenditures, resulting in $60 million and $20 million reductions in the related amortization expense for 2024 and 2023, respectively. Compliance costs incurred were $300 million in 2023 and are expected to be $305 million and $330 million in 2024 and 2025, respectively. The CCR ARO costs are expected to be revised for actual expenditures and updated estimates through future annual compliance filings. Further, under the 2022 ARP, Georgia Power's retail ROE is set at 10.50% and its equity ratio is set at 56%. Earnings will be evaluated against a retail ROE range of 9.50% to 11.90%. Any retail earnings above 11.90% will be shared, with 40% being applied to reduce regulatory assets, 40% directly refunded to customers, and the remaining 20% retained by Georgia Power. There will be no recovery of any earnings shortfall below 9.50% on an actual basis. However, if at any time during the term of the 2022 ARP, Georgia Power projects that its retail earnings will be below 9.50% for any calendar year, it may petition the Georgia PSC for implementation of the Interim Cost Recovery (ICR) tariff to adjust Georgia Power's retail rates to achieve a 9.50% ROE. The Georgia PSC would have 90 days to rule on Georgia Power's request. The ICR tariff would expire at the earlier of January 1, 2026 or the end of the calendar year in which the ICR tariff becomes effective. In lieu of requesting implementation of an ICR tariff, or if the Georgia PSC chooses not to implement the ICR tariff, Georgia Power may file a full rate case. In 2023, Georgia Power's retail ROE was within the allowed retail ROE range. Except as provided above, Georgia Power will not file for a general base rate increase while the 2022 ARP is in effect. Georgia Power is required to file a general base rate case by July 1, 2025, in response to which the Georgia PSC would be expected to determine whether the 2022 ARP should be continued, modified, or discontinued. 2019 ARP The Georgia PSC approved the following tariff adjustments under the 2019 ARP effective January 1 2022:
Tariff |  |  | 2022
|  |  | (in millions)
Traditional base |  |  | $ | 192 |
ECCR |  |  | (12) |
DSM |  |  | (25) |
MFF |  |  | 2 |
Total |  |  | $ | 157 |
In the 2019 ARP, the Georgia PSC approved recovery through the ECCR tariff of the estimated under recovered balance of CCR ARO compliance costs. Under the 2019 ARP, the under recovered balance at December 31, 2019 and compliance costs for 2020 were recovered over the three-year period ended December 31, 2022. Recovery of estimated compliance costs for 2021 and 2022 are being recovered over four-year periods beginning January 1 of each respective year, as authorized under the 2019 ARP and modified under the 2022 ARP, with recovery of construction contingency beginning in the year following actual expenditure. The CCR ARO costs recovered through the ECCR tariff are revised for actual expenditures and updated estimates through annual compliance filings, which resulted in an approximate $10 million increase effective January 1, 2022 in the related cost recovery. Georgia Power's retail ROE under the 2019 ARP was set at 10.50% and earnings were evaluated against a retail ROE range of 9.50% to 12.00%. Any retail earnings above 12.00% were shared, with 40% applied to reduce regulatory assets, 40% directly refunded to customers, and the remaining 20% retained by Georgia Power. In 2020, Georgia Power's retail ROE was within the allowed retail ROE range. In 2021, Georgia Power's retail ROE exceeded 12.00%, and Georgia Power reduced regulatory assets by approximately $5 million and accrued approximately $5 million which was refunded to customers in 2022. In 2022, Georgia Power's retail ROE exceeded 12.00%, and Georgia Power reduced regulatory assets by $117 million and refunded $117 million to customers through bill credits in the first quarter 2023. Integrated Resource Plans In July 2022, the Georgia PSC approved Georgia Power's 2022 IRP, as modified by a stipulated agreement among Georgia Power, the staff of the Georgia PSC, and certain intervenors and as further modified by the Georgia PSC. In the 2022 IRP decision, the Georgia PSC approved, among other things, the certification of six PPAs (including five affiliate PPAs with Southern Power that are subject to approval by the FERC) with capacities of 1,567 MWs beginning in 2024, 380 MWs beginning in 2025, and 228 MWs beginning in 2028, procured through RFPs authorized in the 2019 IRP. See Note 9 for additional information. On October 27, 2023, Georgia Power filed an updated IRP (2023 IRP Update) with the Georgia PSC, which sets forth a plan to support the recent increase in the state of Georgia's projected energy needs since the 2022 IRP. In the 2023 IRP Update, Georgia Power requested the following: •Authority to develop, own, and operate up to 1,400 MWs from three simple cycle combustion turbines at Plant Yates. •Certification of an affiliate PPA with Mississippi Power for 750 MWs, which began January 1, 2024 and will continue through December 2028. •Certification of a non-affiliate PPA for 230 MWs starting the month after conclusion of the 2023 IRP Update proceeding continuing through December 2028. •Authority to develop, own, and operate up to 1,000 MWs of battery energy storage system facilities, including storage systems collocated with existing and new Georgia Power-owned solar facilities. •Approval of transmission projects necessary to support the generation resources requested in the 2023 IRP Update. The 2023 IRP Update assumes a retirement date at the end of 2035 for Plant Bowen Units 1 and 2 (1,400 MWs). Georgia Power expects to make a formal recommendation in the 2025 IRP on the retirement or continued operations for Plant Bowen Units 1 and 2, as well as evaluate extending the operation of Plant Scherer Unit 3 (614 MWs based on 75% ownership) and Plant Gaston Units 1 through 4 (500 MWs based on 50% ownership through SEGCO) beyond the retirement dates in 2028 that were approved in the 2022 IRP. See Note 7 under "SEGCO" for additional information. Georgia Power expects the Georgia PSC to render a final decision on the 2023 IRP Update on April 16, 2024. On January 12, 2024, Georgia Power entered into an Agreement for Engineering, Procurement, and Construction with Mitsubishi Power Americas, Inc. and Black & Veatch Construction, Inc. to construct three 442-MW simple cycle combustion turbine units at Plant Yates (Plant Yates Units 8, 9, and 10), which are expected to be placed in service in the fourth quarter 2026, the second quarter 2027, and the third quarter 2027, respectively. The ultimate outcome of these matters cannot be determined at this time. In August 2022, Restore Chattooga Gorge Coalition (RCG) filed a petition in the Superior Court of Fulton County, Georgia against Georgia Power and the Georgia PSC. The petition challenged Georgia Power's plan to expend $115 million to modernize Plant Tugalo (a hydro facility), as approved in the 2019 IRP, and sought judicial review of the Georgia PSC's order in the 2022 IRP proceeding with respect to the denial of RCG's challenge to the modernization plan. On October 23, 2023, the court granted Georgia Power's and the Georgia PSC's motions to dismiss the RCG petition. This matter is now concluded. Fuel Cost Recovery Georgia Power has established fuel cost recovery rates approved by the Georgia PSC. During the second half of 2021, the price of natural gas rose significantly and resulted in an under recovered fuel balance exceeding $200 million. Therefore, in November 2021, the Georgia PSC voted to approve Georgia Power's interim fuel rider, which increased fuel rates by 15%, or approximately $252 million annually, effective January 1, 2022. During 2022, Georgia Power's under recovered fuel balance continued to increase significantly due to higher fuel and purchased power costs. On May 16, 2023, the Georgia PSC approved a stipulation agreement between Georgia Power and the staff of the Georgia PSC to increase annual fuel billings by 54%, or approximately $1.1 billion, effective June 1, 2023. The increase includes a three-year recovery period for $2.2 billion of Georgia Power's under recovered fuel balance at May 31, 2023. Under the approved stipulation agreement, Georgia Power is allowed to adjust its fuel cost recovery rates under an interim fuel rider prior to the next fuel case, subject to a maximum 40% cumulative change, if its under or over recovered fuel balance accumulated since May 31, 2023 exceeds $200 million. Georgia Power is scheduled to file its next fuel case no later than February 28, 2026. Georgia Power's under recovered fuel balance totaled $1.9 billion at December 31, 2023, of which $694 million is included in under recovered fuel clause revenues and under recovered retail fuel clause revenues on Southern Company's and Georgia Power's balance sheets, respectively, and $1.2 billion is included in deferred under recovered retail fuel clause revenues on Southern Company's and Georgia Power's balance sheets. The under recovered fuel balance totaled $2.1 billion at December 31, 2022 and is included in deferred under recovered retail fuel clause revenues on Southern Company's and Georgia Power's balance sheets. Georgia Power's fuel cost recovery mechanism includes costs associated with a natural gas hedging program, as revised and approved by the Georgia PSC, allowing the use of an array of derivative instruments within a 36-month time horizon. Fuel cost recovery revenues as recorded on the financial statements are adjusted for differences in actual recoverable fuel costs and amounts billed in current regulated rates. Accordingly, changes in the billing factor will not have a significant effect on Southern Company's or Georgia Power's revenues or net income but will affect operating cash flows. Storm Damage Recovery Georgia Power defers and recovers certain costs related to damages from major storms as mandated by the Georgia PSC. During 2021 and 2022, Georgia Power recovered $213 million annually under the 2019 ARP. Beginning January 1, 2023, Georgia Power is recovering $31 million annually under the 2022 ARP. At December 31, 2022, Georgia Power's storm damage reserve balance was $83 million and is included in other regulatory liabilities, deferred on Southern Company's balance sheet and other deferred credits and liabilities on Georgia Power's balance sheet. During 2023, significant storms caused damage to Georgia Power's transmission and distribution facilities. The incremental restoration costs related to these storms exceeded the storm damage reserve and were deferred in the regulatory asset for storm damage. At December 31, 2023, Georgia Power's regulatory asset balance related to storm damage was $54 million, of which $31 million is included in other regulatory assets, current and $23 million is included in other regulatory assets, deferred on Southern Company's and Georgia Power's balance sheets. The rate of storm damage cost recovery is expected to be adjusted in future regulatory proceedings as necessary. As a result of this regulatory treatment, costs related to storms are not expected to have a material impact on Southern Company's or Georgia Power's net income but do impact the related operating cash flows. See Note 1 under "Storm Damage and Reliability Reserves" for additional information. Nuclear Construction In 2009, the Georgia PSC certified construction of Plant Vogtle Units 3 and 4, in which Georgia Power holds a 45.7% ownership interest. In 2012, the NRC issued the related combined construction and operating licenses, which allowed full construction of the two AP1000 nuclear units (with electric generating capacity of approximately 1,100 MWs each) and related facilities to begin. Until March 2017, construction on Plant Vogtle Units 3 and 4 continued under the Vogtle 3 and 4 Agreement, which was a substantially fixed price agreement. In connection with the EPC Contractor's bankruptcy filing in March 2017, Georgia Power, acting for itself and as agent for the other Vogtle Owners, entered into several transitional arrangements to allow construction to continue. In July 2017, Georgia Power, acting for itself and as agent for the other Vogtle Owners, entered into the Vogtle Services Agreement, whereby Westinghouse provides facility design and engineering services, procurement and technical support, and staff augmentation on a time and materials cost basis. The Vogtle Services Agreement provides that it will continue until the start-up and testing of Plant Vogtle Units 3 and 4 are complete and electricity is generated and sold from both units. In October 2017, Georgia Power, acting for itself and as agent for the other Vogtle Owners, executed the Bechtel Agreement, under which Bechtel is reimbursed for actual costs plus a base fee and an at-risk fee, subject to adjustment based on Bechtel's performance against cost and schedule targets. Each Vogtle Owner is severally (not jointly) liable for its proportionate share, based on its ownership interest, of all amounts owed to Bechtel under the Bechtel Agreement. See Note 8 under "Long-term Debt – DOE Loan Guarantee Borrowings" for information on the Amended and Restated Loan Guarantee Agreement, including applicable covenants, events of default, and mandatory prepayment events. Cost and Schedule Georgia Power's approximate proportionate share of the remaining estimated capital cost to complete Plant Vogtle Units 3 and 4, including contingency, through the second quarter 2024 is as follows:
| (in millions) |
Base project capital cost forecast(a)(b) | $ | 10,717 |  |
Construction contingency estimate | 36 |  |
Total project capital cost forecast(a)(b) | 10,753 |  |
Net investment at December 31, 2023(b) | (10,564) |  |
Remaining estimate to complete | $ | 189 |  |
(a)Includes approximately $610 million of costs that are not shared with the other Vogtle Owners, including $33 million of construction monitoring costs, and approximately $567 million of incremental costs under the cost-sharing provisions of the joint ownership agreements described below. Excludes financing costs expected to be capitalized through AFUDC of approximately $440 million, of which $417 million had been accrued through December 31, 2023. (b)Net of $1.7 billion received from Toshiba under the Guarantee Settlement Agreement and approximately $188 million in related customer refunds. Georgia Power estimates that its financing costs for construction of Plant Vogtle Units 3 and 4 will total approximately $3.53 billion, of which $3.50 billion had been incurred through December 31, 2023. Georgia Power placed Unit 3 in service on July 31, 2023. As part of its ongoing processes, Southern Nuclear continues to evaluate cost and schedule forecasts for Unit 4 on a regular basis to incorporate current information available, particularly in the areas of start-up testing and related test results and engineering support. As of December 31, 2023, based on completion of construction work and the assessment of start-up and pre-operational testing remaining, Southern Nuclear has an estimated $36 million for construction contingency remaining in the estimate to complete. This contingency is projected to be allocated in the future to address any further Unit 4 schedule extensions or remediation of other issues discovered during start-up testing. Hot functional testing for Unit 4 was completed on May 1, 2023. On July 20, 2023, Southern Nuclear announced that all Unit 4 ITAACs had been submitted to the NRC, and, on July 28, 2023, the NRC published its 103(g) finding that the accepted criteria in the combined license for Unit 4 had been met, which allowed nuclear fuel to be loaded and start-up testing to begin. Fuel load for Unit 4 was completed on August 19, 2023. On October 6, 2023, Georgia Power announced that during start-up and pre-operational testing for Unit 4, Southern Nuclear identified a motor fault in one of four reactor coolant pumps (RCPs). This RCP was replaced with an on-site spare RCP from inventory. On February 1, 2024, Georgia Power announced that during start-up and pre-operational testing for Unit 4, Southern Nuclear identified, and has remediated, vibrations associated with certain piping within the cooling system. Considering the remaining pre-operational testing, Unit 4 is projected to be placed in service during the second quarter 2024. On February 14, 2024, Unit 4 achieved self-sustaining nuclear fission, commonly referred to as initial criticality. With Unit 3's four RCPs operating as designed, Southern Nuclear believes that the motor fault on this single Unit 4 RCP is an isolated event. However, any findings related to the root cause of the motor fault on the single Unit 4 RCP could require engineering changes or remediation related to the other seven Unit 3 and Unit 4 RCPs. The projected schedule for Unit 4 significantly depends on the progression of start-up and pre-operational testing, which may be impacted by equipment or other operational failures. As Unit 4 progresses further through testing, ongoing and potential future challenges may also include the management of contractors and vendors; the availability of materials and parts, and/or related cost escalation; the availability of supervisory and technical support resources; and the timeframe and duration of pre-operational testing. New challenges also may continue to arise as Unit 4 moves further into testing and start-up, which may result in required engineering changes or remediation related to plant systems, structures, or components (some of which are based on new technology that only within the last several years began initial operation in the global nuclear industry at this scale). These challenges may result in further schedule delays and/or cost increases. With the receipt of the NRC's 103(g) findings for Units 3 and 4 in August 2022 and July 2023, respectively, the site is subject to the NRC's operating reactor oversight process and must meet applicable technical and operational requirements contained in its operating license. Various design and other licensing-based compliance matters may result in additional license amendment requests or require other resolution. If any license amendment requests or other licensing-based compliance issues are not resolved in a timely manner, there may be delays in the Unit 4 project schedule that could result in increased costs. The ultimate outcome of these matters cannot be determined at this time. However, any extension of the in-service date beyond June 2024 for Unit 4, including the joint owner cost sharing impacts described below, is estimated to result in additional base capital costs for Georgia Power of up to $25 million per month as well as any additional related construction, support resources, or testing costs. Pursuant to the regulatory orders discussed below, any further changes to the capital cost forecast will not be recoverable through regulated rates and will be required to be charged to income. Such charges could be material. Joint Owner Contracts In November 2017, the Vogtle Owners entered into an amendment to their joint ownership agreements for Plant Vogtle Units 3 and 4 to provide for, among other conditions, additional Vogtle Owner approval requirements. Effective in August 2018, the Vogtle Owners further amended the joint ownership agreements to clarify and provide procedures for certain provisions of the joint ownership agreements related to adverse events that require the vote of the holders of at least 90% of the ownership interests in Plant Vogtle Units 3 and 4 to continue construction (as amended, and together with the November 2017 amendment, the Vogtle Joint Ownership Agreements). The Vogtle Joint Ownership Agreements also confirm that the Vogtle Owners' sole recourse against Georgia Power or Southern Nuclear for any action or inaction in connection with their performance as agent for the Vogtle Owners is limited to removal of Georgia Power and/or Southern Nuclear as agent, except in cases of willful misconduct. Amendments to the Vogtle Joint Ownership Agreements In connection with a September 2018 vote by the Vogtle Owners to continue construction, Georgia Power entered into (i) a binding term sheet (Vogtle Owner Term Sheet) with the other Vogtle Owners and MEAG Power's wholly-owned subsidiaries MEAG Power SPVJ, LLC (MEAG SPVJ), MEAG Power SPVM, LLC (MEAG SPVM), and MEAG Power SPVP, LLC (MEAG SPVP) to take certain actions which partially mitigate potential financial exposure for the other Vogtle Owners, including additional amendments to the Vogtle Joint Ownership Agreements and the purchase of PTCs from the other Vogtle Owners at pre-established prices, and (ii) a term sheet (MEAG Term Sheet) with MEAG Power and MEAG SPVJ to provide up to $300 million of funding with respect to MEAG SPVJ's ownership interest in Plant Vogtle Units 3 and 4 under certain circumstances. In January 2019, Georgia Power, MEAG Power, and MEAG SPVJ entered into an agreement to implement the provisions of the MEAG Term Sheet. In February 2019, Georgia Power, the other Vogtle Owners, and MEAG Power's wholly-owned subsidiaries MEAG SPVJ, MEAG SPVM, and MEAG SPVP entered into certain amendments to the Vogtle Joint Ownership Agreements to implement the provisions of the Vogtle Owner Term Sheet (Global Amendments). Pursuant to the Global Amendments: (i) each Vogtle Owner paid its proportionate share of qualifying construction costs for Plant Vogtle Units 3 and 4 based on its ownership percentage up to the estimated cost at completion (EAC) for Plant Vogtle Units 3 and 4, of which Georgia Power's share is $8.4 billion (VCM 19 Forecast Amount), plus $800 million; (ii) Georgia Power was responsible for 55.7% of actual qualifying construction costs between $800 million and $1.6 billion over the VCM 19 Forecast Amount (resulting in $80 million of potential additional costs to Georgia Power), with the remaining Vogtle Owners responsible for 44.3% of such costs pro rata in accordance with their respective ownership interests; and (iii) Georgia Power was responsible for 65.7% of qualifying construction costs between $1.6 billion and $2.1 billion over the VCM 19 Forecast Amount (resulting in a further $100 million of potential additional costs to Georgia Power), with the remaining Vogtle Owners responsible for 34.3% of such costs pro rata in accordance with their respective ownership interests. The Global Amendments provide that if the EAC was revised and exceeded the VCM 19 Forecast Amount by more than $2.1 billion, each of the other Vogtle Owners had a one-time option at the time the project budget cost forecast was so revised to tender a portion of its ownership interest to Georgia Power in exchange for Georgia Power's agreement to pay 100% of such Vogtle Owner's remaining share of total construction costs in excess of the VCM 19 Forecast Amount plus $2.1 billion. In addition, pursuant to the Global Amendments, the holders of at least 90% of the ownership interests in Plant Vogtle Units 3 and 4 must vote to continue construction if certain adverse events (Project Adverse Events) occur, including, among other events: (i) the bankruptcy of Toshiba; (ii) the termination or rejection in bankruptcy of certain agreements, including the Vogtle Services Agreement, the Bechtel Agreement, or the agency agreement with Southern Nuclear; (iii) Georgia Power's public announcement of its intention not to submit for rate recovery any portion of its investment in Plant Vogtle Units 3 and 4 or the Georgia PSC determines that any of Georgia Power's costs relating to the construction of Plant Vogtle Units 3 and 4 will not be recovered in retail rates, excluding any additional amounts paid by Georgia Power on behalf of the other Vogtle Owners pursuant to the Global Amendments described above and the first 6% of costs during any six-month VCM reporting period that are disallowed by the Georgia PSC for recovery, or for which Georgia Power elects not to seek cost recovery, through retail rates; and (iv) an incremental extension of one year or more from the seventeenth VCM report estimated in-service dates of November 2021 and November 2022 for Units 3 and 4, respectively. The schedule extension announced in February 2022 triggered the requirement for a vote to continue construction and all the Vogtle Owners voted to continue construction. The filing of Georgia Power's prudency application with the Georgia PSC, which included Georgia Power's public announcement of its intention not to submit for rate recovery an amount that is greater than the first 6% of costs during any six-month VCM reporting period, triggered the requirement for a vote to continue construction and all the Vogtle Owners voted to continue construction. See additional information on Georgia Power's prudency application filing below. In September 2022, Georgia Power and MEAG Power reached an agreement to resolve a dispute regarding the cost-sharing and tender provisions of the Global Amendments. Under the terms of the agreement, among other items, (i) MEAG Power will not exercise its tender option and will retain its full ownership interest in Plant Vogtle Units 3 and 4; (ii) Georgia Power will reimburse a portion of MEAG Power's costs of construction for Plant Vogtle Units 3 and 4 as such costs are incurred and with no further adjustment for force majeure costs, which payments will total approximately $92 million based on the current project capital cost forecast; and (iii) Georgia Power will reimburse 20% of MEAG Power's costs of construction with respect to any amounts over the current project capital cost forecast, with no further adjustment for force majeure costs. In addition, MEAG Power agreed to vote to continue construction upon occurrence of a Project Adverse Event unless the commercial operation date of either of Plant Vogtle Unit 3 or Unit 4 is not projected to occur by December 31, 2025. On October 5, 2023 and October 17, 2023, Georgia Power reached agreements with OPC and Dalton, respectively, to resolve its respective dispute with each of OPC and Dalton regarding the cost-sharing and tender provisions of the Global Amendments. Under the terms of the agreements with OPC and Dalton, among other items, (i) each of OPC and Dalton retracted its exercise of the tender option and will retain its full ownership interest in Plant Vogtle Units 3 and 4, (ii) Georgia Power made payments immediately after execution of the agreements of $308 million and $17 million to OPC and Dalton, respectively, representing payment for a portion of each of OPC's and Dalton's costs of construction for Plant Vogtle Units 3 and 4 previously incurred, (iii) Georgia Power will pay a portion of each of OPC's and Dalton's further costs of construction for Plant Vogtle Units 3 and 4 as such costs are incurred and with no further adjustment for force majeure costs, which payments will be in an aggregate amount of approximately $105 million and $6 million for OPC and Dalton, respectively, based on the current project capital cost forecast, and (iv) Georgia Power will pay 66% of each of OPC's and Dalton's costs of construction with respect to any amounts above the current project capital cost forecast, with no further adjustment for force majeure costs. Georgia Power recorded pre-tax charges to income through the fourth quarter 2022 of $407 million ($304 million after tax) associated with the cost-sharing provisions of the Global Amendments, including the settlement with MEAG Power. Based on the current project capital cost forecast and the settlements with OPC and Dalton described above, Georgia Power recorded a pre-tax charge to income of approximately $160 million ($120 million after tax) in the third quarter 2023. These charges are included in the total project capital cost forecast and will not be recovered from retail customers. The ultimate impact of these matters on the project capital cost forecast for Plant Vogtle Units 3 and 4 cannot be determined at this time. Regulatory Matters In 2009, the Georgia PSC voted to certify construction of Plant Vogtle Units 3 and 4 with a certified capital cost of $4.418 billion. In addition, in 2009 the Georgia PSC approved inclusion of the Plant Vogtle Units 3 and 4 related CWIP accounts in rate base, and the State of Georgia enacted the Georgia Nuclear Energy Financing Act, which allows Georgia Power to recover financing costs for Plant Vogtle Units 3 and 4. Financing costs are recovered on all applicable certified costs through annual adjustments to the NCCR tariff up to the certified capital cost of $4.418 billion. At December 31, 2023, Georgia Power had recovered approximately $3.0 billion of financing costs. Financing costs related to capital costs above $4.418 billion up to $7.562 billion approved for recovery as described below are being recognized through AFUDC and will be recovered through retail rates over the life of Plant Vogtle Units 3 and 4; however, Georgia Power is not recording AFUDC related to any capital costs in excess of $7.562 billion. In December 2022, the Georgia PSC approved Georgia Power's filing to increase the NCCR tariff by $36 million annually, effective January 1, 2023. On November 1, 2023, Georgia Power filed a request to continue for 2024 the NCCR tariff that was effective during 2023. The staff of the Georgia PSC accepted the proposal and no further approval from the Georgia PSC was required. See additional information below on AFUDC and the NCCR tariff following commercial operation of Unit 4. In 2016, the Georgia PSC voted to approve a settlement agreement (Vogtle Cost Settlement Agreement) resolving certain prudency matters in connection with the fifteenth VCM report. In January 2018, the Georgia PSC issued an order approving Georgia Power's seventeenth VCM report and modified the Vogtle Cost Settlement Agreement. The Vogtle Cost Settlement Agreement, as modified by the January 2018 order, resolved certain regulatory matters related to Plant Vogtle Units 3 and 4 including, but not limited to: (i) a revised capital cost forecast of $7.3 billion (after reflecting the impact of payments received under the Guarantee Settlement Agreement and related customer refunds) was found reasonable; (ii) confirmed that a prudence proceeding on cost recovery would occur following Unit 4 fuel load, consistent with applicable Georgia law; (iii) reduced the ROE used to calculate the NCCR tariff (a) from 10.95% (the ROE rate setting point authorized by the Georgia PSC at that time) to 10.00% effective January 1, 2016, (b) from 10.00% to 8.30%, effective January 1, 2020, and (c) from 8.30% to 5.30%, effective January 1, 2021 (provided that the ROE in no case will be less than Georgia Power's average cost of long-term debt); and (iv) reduced the ROE used for AFUDC equity for Plant Vogtle Units 3 and 4 from 10.00% to Georgia Power's average cost of long-term debt, effective January 1, 2018. The January 2018 order also stated that if Plant Vogtle Units 3 and 4 are not commercially operational by June 1, 2021 and June 1, 2022, respectively, the ROE used to calculate the NCCR tariff will be further reduced by 10 basis points each month (but not lower than Georgia Power's average cost of long-term debt) until the respective Unit is commercially operational. The ROE reductions negatively impacted earnings by approximately $310 million, $300 million, and $270 million in 2023, 2022, and 2021, respectively, and are estimated to have a negative earnings impact of approximately $90 million in 2024. In 2021, the Georgia PSC approved an order under which Georgia Power would include in rate base an allocation of $2.1 billion to Plant Vogtle Unit 3 and the Common Facilities from the $3.6 billion of Plant Vogtle Units 3 and 4 costs previously deemed prudent by the Georgia PSC and would recover the related depreciation expense through retail base rates effective the month after Unit 3 is placed in service. In compliance with the Georgia PSC order, Georgia Power increased annual retail base rates by $318 million effective August 1, 2023 based on the in-service date of July 31, 2023 for Unit 3. The related increase in annual retail base rates included recovery of all projected operations and maintenance expenses for Unit 3 and the Common Facilities and other related costs of operation, partially offset by the related PTCs. Financing costs (debt and equity) on the remaining portion of the total Unit 3 and the Common Facilities construction costs continue to be recovered through the NCCR tariff or deferred. Georgia Power is deferring as a regulatory asset the debt component of financing costs ($14 million at December 31, 2023) as well as the remaining depreciation expense ($17 million at December 31, 2023) until Unit 4 costs are placed in retail base rates. The equity component of financing costs ($23 million at December 31, 2023) represents an unrecognized ratemaking amount that is not reflected on Georgia Power's balance sheets. This amount will be recognized in Georgia Power's income statements in the periods it is billable to customers. On August 19, 2023, fuel load for Unit 4 was completed, and, on August 30, 2023, Georgia Power filed an application to adjust rates to include reasonable and prudent Plant Vogtle Units 3 and 4 costs (Application). On December 19, 2023, the Georgia PSC voted to approve the Application as modified by the related stipulated agreement (Prudency Stipulation) among Georgia Power, the staff of the Georgia PSC, and certain intervenors. While recognizing the Prudency Stipulation, the Application provided the necessary support to justify the reasonableness, prudence, and recovery of $8.826 billion in total construction and capital costs, $1.07 billion in associated retail rate base items, and the operating costs related to the full operation and output of Plant Vogtle Units 3 and 4. Under the terms of the approved Prudency Stipulation, Georgia Power will recover $7.562 billion in total construction and capital costs and associated retail rate base items of $1.02 billion, which includes AFUDC financing costs above $4.418 billion (the Georgia PSC-certified amount) up to $7.562 billion. Georgia Power will also recover projected operations and maintenance expenses, depreciation expense, nuclear decommissioning accruals, and property taxes, net of projected PTCs. After considering construction and capital costs already in retail base rates of $2.1 billion and $362 million of associated retail rate base items (approved by the Georgia PSC in 2021) and upon achieving commercial operation of Unit 4, Georgia Power will include in retail rate base the remaining $5.462 billion of construction and capital costs as well as $656 million of associated retail rate base items. When the rate adjustment occurs, Georgia Power's NCCR tariff will cease to be collected and financing costs will be included in Georgia Power's general retail revenue requirements. Further, as included in the approved Prudency Stipulation, if commercial operation for Unit 4 is not achieved by March 31, 2024, Georgia Power's ROE used to determine the NCCR tariff and calculate AFUDC will be reduced to zero, which will result in an estimated negative impact to earnings of approximately $30 million per month until the month following the date commercial operation for Unit 4 is achieved. As of each Unit's respective first refueling outage, if the respective Unit's performance has materially deviated from expected performance, the Georgia PSC may order Georgia Power to credit customers for operations and maintenance expenses or disallow costs associated with the repair or replacement of any system, structure, or component found to have caused the material deviation in performance if proven to be the result of imprudent engineering, construction, procurement, testing, or start-up. Annual retail base revenues will increase approximately $729 million and the average retail base rates will be adjusted by approximately 5% (net of the elimination of the NCCR tariff described above) effective the first day of the month after Unit 4 achieves commercial operation. The approval of the Application and the Prudency Stipulation resolves all issues for determination by the Georgia PSC regarding the reasonableness, prudence, and cost recovery for the remaining Plant Vogtle Units 3 and 4 construction and capital costs not already in retail base rates. As a result of the Georgia PSC's approval of the Prudency Stipulation, Georgia Power recorded a pre-tax credit to income of approximately $228 million ($170 million after tax) in the fourth quarter 2023 to recognize CWIP costs previously charged to income, which are now recoverable through retail rates. Associated AFUDC on these costs was also recognized. The ultimate outcome of these matters cannot be determined at this time. Mississippi Power Mississippi Power's rates and charges for service to retail customers are subject to the regulatory oversight of the Mississippi PSC. Mississippi Power's rates are a combination of base rates and several separate cost recovery clauses for specific categories of costs. These separate cost recovery clauses address such items as fuel and purchased power, ad valorem taxes, property damage, and the costs of compliance with environmental laws and regulations. Costs not addressed through one of the specific cost recovery clauses are expected to be recovered through Mississippi Power's base rates. Performance Evaluation Plan Mississippi Power's retail base rates generally are set under the PEP, a rate plan approved by the Mississippi PSC. In recognition that Mississippi Power's long-term financial success is dependent upon how well it satisfies its customers' needs, PEP includes performance indicators that directly tie customer service indicators to Mississippi Power's allowed ROE. PEP measures Mississippi Power's performance on a 10-point scale as a weighted average of results in three areas: average customer price, as compared to prices of other regional utilities (weighted at 40%); service reliability, measured in percentage of time customers had electric service (40%); and customer satisfaction, measured in a survey of residential customers (20%). Typically, two PEP filings are made for each calendar year: the PEP projected filing in March of the current year and the PEP lookback filing in March of the subsequent year. The annual PEP projected filings utilize a historic test year adjusted for "known and measurable" changes and discounted cash flow and regression formulas to determine base ROE. The PEP lookback filing reflects the actual revenue requirement. In June 2021 and June 2022, the Mississippi PSC approved Mississippi Power's annual retail PEP filings, resulting in annual increases in revenues of approximately $16 million, or 1.8%, and $18 million, or 1.9%, respectively, effective with the first billing cycle of April 2021 and April 2022, respectively. On June 13, 2023, the Mississippi PSC approved Mississippi Power's annual retail PEP filing for 2023 indicating no change in retail rates. Integrated Resource Plan In 2020, the Mississippi PSC issued an order requiring Mississippi Power to incorporate into its 2021 IRP a schedule of early or anticipated retirement of 950 MWs of fossil-steam generation by year-end 2027 to reduce the excess reserve margin Mississippi Power anticipated at that time. The order stated that Mississippi Power will be allowed to defer any retirement-related costs as regulatory assets for future recovery. In 2021, the Mississippi PSC concluded its review of Mississippi Power's 2021 IRP. The 2021 IRP included a schedule to retire Plant Watson Unit 4 (268 MWs) and Mississippi Power's 40% ownership interest in Plant Greene County Units 1 and 2 (103 MWs each) in December 2023, 2025, and 2026, respectively, consistent with each unit's remaining useful life in the most recent approved depreciation studies. In addition, the schedule reflected the early retirement of Mississippi Power's 50% undivided ownership interest in Plant Daniel Units 1 and 2 (502 MWs) by the end of 2027. The Plant Greene County unit retirements require the completion by Alabama Power of transmission and system reliability improvements, as well as agreement by Alabama Power. The remaining net book value of Plant Daniel Units 1 and 2 was approximately $489 million at December 31, 2023 and Mississippi Power is continuing to depreciate these units using the current approved rates. Mississippi Power expects to reclassify the net book value remaining at retirement to a regulatory asset to be amortized over a period to be determined by the Mississippi PSC in future proceedings, consistent with the 2020 order. The Plant Watson and Greene County units are expected to be fully depreciated upon retirement. See Note 3 under "Other Matters – Mississippi Power" for additional information on Plant Daniel Units 1 and 2. In October 2023, Mississippi Power signed an affiliate PPA with Georgia Power for 750 MWs of capacity, which began January 1, 2024 and will continue through December 2028. In order to fulfill this PPA and serve the interests of customers, Mississippi Power now expects electric generating units identified in its 2021 IRP to remain in service beyond the previously indicated dates. Mississippi Power is expected to file its next IRP in April 2024 in accordance with the rules and orders of the Mississippi PSC. The ultimate outcome of these matters cannot be determined at this time. Environmental Compliance Overview Plan In accordance with a 2011 accounting order from the Mississippi PSC, Mississippi Power has the authority to defer in a regulatory asset for future recovery all plant retirement- or partial retirement-related costs resulting from environmental regulations. In June 2021, April 2022, and April 2023, the Mississippi PSC approved Mississippi Power's annual ECO Plan filings, resulting in a decrease in revenues of approximately $9 million annually effective with the first billing cycle of July 2021, an increase in revenues of approximately $1 million annually effective with the first billing cycle of May 2022, and a $3 million annual increase in revenues effective with the first billing cycle of May 2023, respectively. On February 12, 2024, Mississippi Power submitted its annual ECO Plan filing to the Mississippi PSC, which requested a $9 million annual increase in revenues. The ultimate outcome of this matter cannot be determined at this time. Fuel Cost Recovery Mississippi Power annually establishes, and is required to file for an adjustment to, the retail fuel cost recovery factor that is approved by the Mississippi PSC. The Mississippi PSC approved increases of $2 million and $43 million effective in February 2021 and 2022, respectively. In November 2022, Mississippi Power filed a request with the Mississippi PSC to increase retail fuel revenues by $25 million annually effective with the first billing cycle of February 2023 and an additional $25 million annually effective with the first billing cycle of June 2023. On January 10, 2023, the Mississippi PSC voted to defer approval of the filing. Mississippi Power is allowed to maintain current billing rates and continue accruing its weighted-average cost of capital on any under or over fuel recovery balance. On February 6, 2024, the Mississippi PSC approved Mississippi Power's request to increase retail fuel revenues by $18 million annually effective with the first billing cycle of March 2024. The approved filing included the deferral of approximately $61 million of under recovered fuel costs as of October 2023, which is expected to be included in Mississippi Power's next fuel filing. Mississippi Power will continue to accrue its weighted-average cost of capital on any under or over fuel recovery balance. At December 31, 2023, Mississippi Power had $50 million of deferred under recovered r etail fuel clause revenues and $27 million of over recovered retail fuel clause revenues primarily associated with its fuel-hedging program on its balance sheet. At December 31, 2022, under recovered retail fuel costs of approximately $1 million were included in other customer accounts receivable on Mississippi Power's balance sheet. See Note 1 under "Fuel Costs" for additional information. Mississippi Power has wholesale MRA and Market Based (MB) fuel cost recovery factors. Effective with the first billing cycles for January 2022, 2023, and 2024, annual revenues under the wholesale MRA fuel rate increased $11 million an d $22 million and decreased $4 million, re spectively. The wholesale MB fuel rate did not change materially in any period presented. At December 31, 2023 and 2022, wholesale fuel costs were over recovered $5 million and under recovered $6 million, respectively. Mississippi Power's operating revenues are adjusted for differences in actual recoverable fuel cost and amounts billed in accordance with the currently approved cost recovery rate. Accordingly, changes in the billing factor should have no significant effect on Mississippi Power's revenues or net income but will affect operating cash flows. Ad Valorem Tax Adjustment Mississippi Power annually establishes an ad valorem tax adjustment factor that is approved by the Mississippi PSC. Effective with the first billing cycle of May 2021, July 2022, and June 2023, the Mississippi PSC approved changes in annual revenues collected through the ad valorem tax adjustment factor resulting in a $28 million increase, a $5 million increase, and a $7 million decrease, respectively. The 2021 increase included approximately $19 million of ad valorem taxes previously recovered through PEP in accordance with a 2019 rate case settlement agreement. System Restoration Rider Mississippi Power carries insurance for the cost of certain types of damage to generation plants and general property. However, Mississippi Power is self-insured for the cost of storm, fire, and other uninsured casualty damage to its property, including transmission and distribution facilities. As permitted by the Mississippi PSC and the FERC, Mississippi Power accrues for the cost of such damage through an annual expense accrual which is credited to regulatory liability accounts for the retail and wholesale jurisdictions. The cost of repairing actual damage resulting from such events that individually exceed $50,000 is charged to the reserve. Every year, the Mississippi PSC, the MPUS, and Mississippi Power agree on SRR revenue level(s). Mississippi Power's net retail SRR accrual, which includes carrying costs and previously included amortization of related excess deferred income tax benefits, was $11.7 million in 2023, $6.9 million in 2022, and $(1.8) million in 2021. At December 31, 2023 and 2022, the retail property damage reserve balance was $45 million and $37 million, respectively. In 2021, the Mississippi PSC approved Mississippi Power's annual SRR filing, which requested an increase in retail revenues of approximately $9 million annually effective with the first billing cycle of March 2022. On April 4, 2023, th e Mississippi PSC approved Mississippi Power's annual SRR filing, which indicated no change in retail rates. Missi ssippi Power's minimum annual SRR accrual was increased from $8.3 million to $11.7 million. In the event the expected annual charges exceed the annual accrual or the target balance has been met, Mississippi Power and the Mississippi PSC will determine the appropriate change to the annual accrual. Additionally, if PEP earnings are above a certain threshold, Mississippi Power has the ability to apply any required PEP refund as an additional accrual to the property damage reserve in lieu of customer refunds. On February 1, 2024, Mississippi Power submitted its annual SRR filing to the Mississippi PSC, which indicated no change in retail rates. The filing includes a request to increase the minimum annual SRR accrual from $11.7 million to $12.6 million. Reliability Reserve Accounting Order In December 2022, the Mississippi PSC approved an accounting order authorizing Mississippi Power to create a reliability reserve for the purpose of deferring generation, transmission, and distribution reliability-related expenditures for use in a future year. Mississippi Power may make accruals to the reliability reserve each year after meeting with the MPUS and Mississippi PSC staff. Mississippi Power will provide annually, through its capital plan, energy delivery plan, or PEP filing, any amounts to be charged against the reliability reserve during the current year. During 2023 and 2022, Mississippi Power accrue d $11 million and $25 million, respectively, to the reliability reserve. At December 31, 2023 and 2022, the reliability reserve balance was $36 million and $25 million, respectively. Municipal and Rural Associations Tariff Mississippi Power provides wholesale electric service to Cooperative Energy, East Mississippi Electric Power Association, and the City of Collins, all located in southeastern Mississippi, under a long-term, cost-based, FERC-regulated MRA tariff. In 2017, Mississippi Power and Cooperative Energy executed, and the FERC accepted, a Shared Service Agreement (SSA), as part of the MRA tariff, under which Mississippi Power and Cooperative Energy share in providing electricity to the Cooperative Energy delivery points under the tariff. In August 2022, the FERC accepted an amended SSA between Mississippi Power and Cooperative Energy, effective July 1, 2022, under which Cooperative Energy will continue to decrease its use of Mississippi Power's generation services under the MRA tariff up to 2.5% annually through 2035. At December 31, 2023, Mississippi Power is serving approximately 390 MWs of Cooperative Energy's annual demand. Beginning in 2036, Cooperative Energy will provide 100% of its electricity requirements at the MRA delivery points under the tariff. Neither party has the option to cancel the amended SSA. On October 27, 2023, the FERC approved a settlement agreement filed by Mississippi Power and Cooperative Energy on July 31, 2023 related to Mississippi Power's July 2022 request for a $23 million increase in annual wholesale base revenues under the MRA tariff. The settlement agreement provides for a $16 million increase in annual wholesale base revenues, effective September 14, 2022, and a refund to customers of approximately $6 million primarily related to the difference between the approved rates and interim rates. Southern Company Gas Utility Regulation and Rate Design The natural gas distribution utilities are subject to regulation and oversight by their respective state regulatory agencies. Rates charged to customers vary according to customer class (residential, commercial, or industrial) and rate jurisdiction. These agencies approve rates designed to provide the opportunity to generate revenues to recover all prudently-incurred costs, including a return on rate base sufficient to pay interest on debt and provide a reasonable ROE. As a result of operating in a deregulated environment, Atlanta Gas Light earns revenue by charging rates to its customers based primarily on monthly fixed charges that are set by the Georgia PSC and adjusted periodically. The Marketers add these fixed charges when billing their respective customers. This mechanism, called a straight-fixed-variable rate design, minimizes the seasonality of Atlanta Gas Light's revenues since the monthly fixed charge is not volumetric or directly weather dependent. With the exception of Atlanta Gas Light, the earnings of the natural gas distribution utilities can be affected by customer consumption patterns that are largely a function of weather conditions and price levels for natural gas. Specifically, customer demand substantially increases during the Heating Season when natural gas is used for heating purposes. Southern Company Gas has various mechanisms, such as weather and revenue normalization mechanisms and weather derivative instruments, that limit exposure to weather changes within typical ranges in these utilities' respective service territories. In addition to natural gas cost recovery mechanisms, other cost recovery mechanisms and regulatory riders, which vary by utility, allow recovery of certain costs, such as those related to infrastructure replacement programs as well as environmental remediation, energy efficiency plans, and bad debts. In traditional rate designs, utilities recover a significant portion of the fixed customer service and pipeline infrastructure costs based on assumed natural gas volumes used by customers. With the exception of Chattanooga Gas, the natural gas distribution utilities have decoupled regulatory mechanisms that Southern Company Gas believes encourage conservation by separating the recoverable amount of these fixed costs from the amounts of natural gas used by customers. See "Rate Proceedings" herein for additional information. Also see "Infrastructure Replacement Programs and Capital Projects" herein for additional information regarding infrastructure replacement programs at certain of the natural gas distribution utilities. The following table provides regulatory information for Southern Company Gas' natural gas distribution utilities:
| Nicor Gas |  | Atlanta Gas Light |  | Virginia Natural Gas |  | Chattanooga Gas
Authorized ROE at December 31, 2023 | 9.51% |  | 10.25% |  | 9.70% |  | 9.80%
Weather normalization mechanisms(a) |  |  |  |  | ü |  | ü
Decoupled, including straight-fixed-variable rates(b) | ü |  | ü |  | ü |  |
Regulatory infrastructure program rate(c) | ü |  | ü |  | ü |  | ü
Bad debt rider(d) | ü |  |  |  | ü |  | ü
Energy efficiency plan(e) | ü |  |  |  | ü |  |
Annual base rate adjustment mechanism(f) |  |  | ü |  |  |  | ü
Year of last base rate case decision | 2023 |  | 2019 |  | 2023 |  | 2018
(a)Designed to help stabilize operating results by allowing recovery of costs in the event of unseasonal weather, but are not direct offsets to the potential impacts on earnings of weather and customer consumption. (b)Allows for recovery of fixed customer service costs separately from assumed natural gas volumes used by customers and provides a benchmark level of revenue for recovery. (c)See "Infrastructure Replacement Programs and Capital Projects" herein for additional information. Chattanooga Gas' pipeline replacement program costs are recovered through its annual base rate review mechanism. (d)The recovery (refund) of bad debt expense over (under) an established benchmark expense. The gas portion of bad debt expense is recovered through purchased gas adjustment mechanisms. Nicor Gas also has a rider to recover the non-gas portion of bad debt expense. (e)Recovery of costs associated with plans to achieve specified energy savings goals. (f)Regulatory mechanism allowing annual adjustments to base rates up or down based on authorized ROE and/or ROE range. Infrastructure Replacement Programs and Capital Projects In addition to capital expenditures recovered through base rates by each of the natural gas distribution utilities, Nicor Gas and Virginia Natural Gas have separate rate riders that provide timely recovery of capital expenditures for specific infrastructure replacement programs and Atlanta Gas Light has a separate rate rider that provides for the timely recovery of capital expenditures for a specific reinforcement capital program. Total capital expenditures incurred during 2023 for all gas distribution operations were $1.6 billion. The following table and discussions provide updates on the infrastructure replacement programs and capital projects at the natural gas distribution utilities at December 31, 2023. These programs are risk-based and designed to update and replace cast iron, bare steel, and mid-vintage plastic materials or expand Southern Company Gas' distribution systems to improve reliability and meet operational flexibility and growth.
Utility |  | Program |  |  |  | Recovery |  | Capital Expenditures in 2023 |  | Capital Expenditures Since Project Inception |  | Pipe Installed Since Project Inception |  | Scope of Program |  | Program Duration |  | Last Year of Program
|  |  |  |  |  |  |  | (in millions) |  | (miles) |  | (miles) |  | (years) |  |
Nicor Gas |  | Investing in Illinois Qualifying Infrastructure Plant(*) |  |  |  | Rider |  | $ | 365 |  |  | $ | 3,228 |  |  | 1,367 |  |  | 1,367 |  |  | 9 |  | 2023
Virginia Natural Gas |  | SAVE |  |  |  | Rider |  | 75 |  |  | 486 |  |  | 567 |  |  | 695 |  |  | 13 |  | 2024
Atlanta Gas Light |  | System Reinforcement Rider |  |  |  | Rider |  | 104 |  |  | 180 |  |  | 20 |  |  | N/A |  | 3 |  | 2024
Chattanooga Gas |  | Pipeline Replacement Program |  |  |  | Rate Base |  | 9 |  |  | 16 |  |  | 15 |  |  | 73 |  |  | 7 |  | 2027
Total |  |  |  |  |  |  |  | $ | 553 |  |  | $ | 3,910 |  |  | 1,969 |  |  | 2,135 |  |  |  |  |
(*)Included replacement of pipes, compressors, and transmission mains along with other improvements such as new meters. This program ended November 30, 2023 with all expenditures placed in service. Recovery of program costs is described under "Nicor Gas" herein. Nicor Gas Illinois legislation allows Nicor Gas to provide more widespread safety and reliability enhancements to its distribution system through 2023 and stipulates that rate increases to customers as a result of any infrastructure investments shall not exceed a cumulative annual average of 4.0% or, in any given year, 5.5% of base rate revenues. In 2014, the Illinois Commission approved the nine-year regulatory infrastructure program, Investing in Illinois, which concluded in 2023 and is subject to annual review, as discussed further below. In accordance with orders from the Illinois Commission, Nicor Gas recovers program costs incurred through a separate rider and base rates. See "Rate Proceedings – Nicor Gas" herein for additional information. On June 15, 2023, the Illinois Commission concluded its review of the Qualifying Infrastructure Plant (QIP) capital investments by Nicor Gas for calendar year 2019 under the QIP rider, also referred to as Investing in Illinois program. The Illinois Commission disallowed $32 million of the $415 million of capital investments commissioned in 2019, together with the related return on investment. Nicor Gas recorded a pre-tax charge to income in the second quarter 2023 of $38 million ($28 million after tax) associated with the disallowance of capital investments placed in service in 2019. The disallowance is reflected on the statement of income as an $8 million reduction to revenues and $30 million in estimated loss on regulatory disallowance. On August 3, 2023, the Illinois Commission denied a rehearing request filed by Nicor Gas. On August 24, 2023, Nicor Gas filed a notice of appeal with the Illinois Appellate Court. Nicor Gas defends these investments in infrastructure as prudently incurred. The following table provides a summary of QIP capital investments during the nine-year program:
Year | Status of QIP Annual Review Proceeding | Capital Investments |  | Disallowed |  | Month of Disallowance
|  | (in millions) |  |
2015 – 2018 | Complete | $ | 1,246 |  |  | $ | — |  |  |
2019 | Complete(a) | 415 |  |  | 32 |  |  | June 2023
2020 | Filed March 2021 | 402 |  | (b) |  |  |
2021 | Filed March 2022 | 392 |  | (b) |  |  |
2022 | Filed March 2023 | 408 |  | (b) | 6 |  | (a)(c) | November 2023
2023 | To be filed by March 20, 2024 | 365 |  | (b) | 25 |  | (a)(c) | November 2023
| $ | 3,228 |  |  | $ | 63 |  |  |
(a)Appealed to the Illinois Appellate Court. (b)Capital investments are subject to the required QIP annual review proceeding; years 2020 through 2022 are pending with the Illinois Commission. (c)Disallowed in Nicor Gas' 2023 general base rate case proceeding. See "Rate Proceedings – Nicor Gas" herein for additional information regarding the Illinois Commission's disallowance of certain capital investments. Any further cost disallowances by the Illinois Commission in the pending cases could be material to the financial statements of Southern Company Gas. The ultimate outcome of these matters cannot be determined at this time. Virginia Natural Gas The SAVE program, an accelerated infrastructure replacement program, allows Virginia Natural Gas to continue replacing aging pipeline infrastructure through 2024. The program includes authorized annual investments of $60 million in 2021 and $70 million in each year from 2022 through 2024, with a total potential variance of up to $5 million allowed for the program, for a maximum total investment over the six-year term (2019 through 2024) of $365 million. O n February 9, 2024, Virginia Natural Gas filed with the Virginia Commission a request to extend the existing SAVE program through 2029. The request includes investments of $70 million in each year from 2025 through 2029, with a potential variance of up to $5 million allowed for the program, for a maximum total investment over the five-year extension (2025 through 2029) of $355 million. Virginia Natural Gas expects the Virginia Commission to issue a final order on this matter in the second quarter 2024. The ultimate outcome of this matter cannot be determined at this time. The SAVE program is subject to annual review by the Virginia Commission. In accordance with the base rate case approved by the Virginia Commission in 2023, Virginia Natural Gas is recovering program costs incurred prior to January 1, 2023 through base rates. Program costs incurred subsequent to January 1, 2023 are currently being recovered through a separate rider and are subject to future base rate case proceedings. See "Rate Proceedings – Virginia Natural Gas" herein for additional information. Atlanta Gas Light In 2019, the Georgia PSC approved the continuation of GRAM as part of Atlanta Gas Light's 2019 rate case order. Various infrastructure programs previously authorized by the Georgia PSC, including the Integrated Vintage Plastic Replacement Program to replace aging plastic pipe and the Integrated System Reinforcement Program to upgrade Atlanta Gas Light's distribution system and LNG facilities in Georgia, continue under GRAM and the recovery of and return on the infrastructure program investments are included in annual base rate adjustments. The amounts to be recovered through rates related to allowed, but not incurred, costs have been quantified as an unrecognized ratemaking amount that is not reflected on the balance sheets. These allowed costs are primarily the equity return on the capital investment under the infrastructure programs in place prior to GRAM and are being recovered through GRAM and base rates until the earlier of the full recovery of such amounts or December 31, 2025. The under recovered balance at December 31, 2023 was $44 million, including $23 million of unrecognized equity return, and is expected to be recovered by December 31, 2025. The Georgia PSC reviews Atlanta Gas Light's performance annually under GRAM. See "Unrecognized Ratemaking Amounts" herein for additional information. Atlanta Gas Light and the staff of the Georgia PSC previously agreed to a variation of the Integrated Customer Growth Program to extend pipeline facilities to serve customers in areas without pipeline access and create new economic development opportunities in Georgia. A separate tariff provides recovery of up to $15 million annually for strategic economic development projects approved by the Georgia PSC. See "Rate Proceedings – Atlanta Gas Light" herein for additional information regarding the Georgia PSC's 2021 approval of Atlanta Gas Light's GRAM filing and Integrated Capacity and Delivery Plan. The Georgia PSC also approved a new System Reinforcement Rider for authorized large pressure improvement and system reliability projects, which is expected to recover related capital investments totaling $286 million for the years 2022 through 2024, of which $104 million and $76 million was incurred in 2023 and 2022, respectively. Chattanooga Gas In 2021, the Tennessee Public Utilities Commission approved Chattanooga Gas' pipeline replacement program to replace approximately 73 miles of distribution main over a seven-year period. The estimated total cost of the program is $118 million, which will be recovered through Chattanooga Gas' annual base rate review mechanism. Natural Gas Cost Recovery With the exception of Atlanta Gas Light, the natural gas distribution utilities are authorized by the relevant regulatory agencies in the states in which they serve to use natural gas cost recovery mechanisms that adjust rates to reflect changes in the wholesale cost of natural gas and ensure recovery of all costs prudently incurred in purchasing natural gas for customers. The natural gas distribution utilities defer or accrue the difference between the actual cost of natural gas and the amount of commodity revenue earned in a given period. The deferred or accrued amount is either billed or refunded to customers prospectively through adjustments to the commodity rate. Deferred natural gas costs are reflected as regulatory assets and accrued natural gas costs are reflected as regulatory liabilities. Natural gas costs generally do not have a significant effect on Southern Company's or Southern Company Gas' net income, but could have a significant effect on cash flows. Since Atlanta Gas Light does not sell natural gas directly to its end-use customers, it does not utilize a traditional natural gas cost recovery mechanism. However, Atlanta Gas Light does maintain natural gas inventory for the Marketers in Georgia and recovers the cost through recovery mechanisms approved by the Georgia PSC. At December 31, 2023, the over recovered balance was $214 million, which was included in natural gas cost over recovery on Southern Company's and Southern Company Gas' balance sheets. At December 31, 2022, the under recovered balance was $108 million, which was included in natural gas cost under recovery on Southern Company's and Southern Company Gas' balance sheets. Rate Proceedings Nicor Gas In 2021, the Illinois Commission approved a $240 million annual base rate increase, which became effective November 24, 2021. The base rate increase included $94 million related to the recovery of program costs under the Investing in Illinois program and was based on a ROE of 9.75% and an equity ratio of 54.5%. On November 16, 2023, the Illinois Commission approved a $223 million annual base rate increase for Nicor Gas, which became effe ctive December 1, 2023. The base rate increase was based on a return on equity of 9.51% and an equity ratio of 50.00%. In connection with Nicor Gas' general base rate case proceeding, the Illinois Commission disallowed $126.8 million of capital investments that have been completed or planned to be completed through December 31, 2024. This includes $31 million for capital investments placed in service in 2022 and 2023 under the Investing in Illinois program and $95.9 million for other transmission and distribution capital investments. Nicor Gas recorded a pre-tax charge to income in the fourth quarter 2023 of $58 million ($44 million after tax) associated with the disallowances, with the remaining $69 million related to prospective projects that will be postponed and/or reevaluated. The disallowance is reflected on the statement of income in estimated loss on regulatory disallowance. See "Infrastructure Replacement Programs and Capital Projects – Nicor Gas" herein for additional information regarding the Illinois Commission's disallowance of certain capital investments. On January 3, 2024, the Illinois Commission denied a request by Nicor Gas for rehearing on the base rate case disallowances associated with capital investment, as well as on other issues determined in the Illinois Commission's November 16, 2023 base rate case decision. On February 6, 2024, Nicor Gas filed a notice of appeal with the Illinois Appellate Court related to the Illinois Commission's rate case ruling. The ultimate outcome of this matter cannot be determined at this time. Atlanta Gas Light The Georgia PSC evaluates Atlanta Gas Light's earnings against a ROE range of 10.05% to 10.45%, with disposition of any earnings above 10.45% to be determined by the Georgia PSC. Additionally, the Georgia PSC allows inclusion in base rates of the recovery of and return on the infrastructure program investments, including, but not limited to, GRAM adjustments. GRAM filing rate adjustments are based on an authorized ROE of 10.25%. GRAM adjustments for 2021 could not exceed 5% of 2020 base rates. The 5% limitation does not set a precedent in any future rate proceedings by Atlanta Gas Light. In April 2021, Atlanta Gas Light filed its Integrated Capacity and Delivery Plan (i-CDP) with the Georgia PSC, which included a series of ongoing and proposed pipeline safety, reliability, and growth programs for the next 10 years (2022 through 2031), as well as the required capital investments and related costs to implement the programs. The i-CDP reflected capital investments totaling approximately $0.5 billion to $0.6 billion annually. In November 2021, the Georgia PSC approved a stipulation agreement between Atlanta Gas Light and the staff of the Georgia PSC, under which, for the years 2022 through 2024, Atlanta Gas Light will incrementally reduce its combined GRAM and System Reinforcement Rider request by 10% through Atlanta Gas Light's GRAM mechanism, which resulted in a reduction of $5 million for 2022, $7 million for 2023, and $9 million for 2024. The stipulation agreement also provided for $1.7 billion of total capital investment for the years 2022 through 2024. In November 2021, December 2022, and December 2023, the Georgia PSC approved Atlanta Gas Light's annual GRAM filings, which resulted in an annual rate increase of $43 million effective January 1, 2022, an annual rate increase of $53 million effective January 1, 2023, and an annual rate increase of $53 million effective January 1, 2024, respectively. On February 1, 2024, Atlanta Gas Light filed its triennial i-CDP with the Georgia PSC, which included a series of ongoing and proposed pipeline safety, reliability, and growth programs for the next 10 years (2025 through 2034), as well as the required capital investments and related costs to implement the programs. The i-CDP reflected capital investments totaling approximately $0.7 billion to $1.0 billion annually. Atlanta Gas Light expects the Georgia PSC to issue a final order on this matter in the third quarter 2024. The ultimate outcome of this matter cannot be determined at this time. Virginia Natural Gas In 2021, the Virginia Commission approved a stipulation agreement related to Virginia Natural Gas' 2020 general rate case filing, which allowed for a $43 million increase in annual base rate revenues, including $14 million related to the recovery of investments under the SAVE program, based on a ROE of 9.5% and an equity ratio of 51.9%. Interim rates became effective as of November 1, 2020, subject to refund, based on Virginia Natural Gas' original requested increase of approximately $50 million. Refunds to customers related to the difference between the approved rates effective October 1, 2021 and the interim rates were completed during the fourth quarter 2021. On August 28, 2023, the Virginia Commission approved a stipulation agreement related to Virginia Natural Gas' August 2022 general base rate case filing, which allowed for a $48 million increase in annual base rate revenues based on a ROE of 9.70% and an equity ratio of 49.06%. Interim rates became effective as of January 1, 2023, subject to refund, based on Virginia Natural Gas' original requested increase of approximately $69 million. Refunds to customers related to the difference between the approved rates effective September 1, 2023 and the interim rates were completed during the fourth quarter 2023. Unrecognized Ratemaking Amounts The following table illustrates Southern Company Gas' authorized ratemaking amounts that are not recognized on its balance sheets. These amounts are primarily comprised of an allowed equity rate of return on assets associated with certain regulatory infrastructure programs. These amounts will be recognized as revenues in Southern Company Gas' financial statements in the periods they are billable to customers, the majority of which will be recovered by 2025.
| December 31, 2023 |  | December 31, 2022
| (in millions)
Atlanta Gas Light | $ | 23 |  |  | $ | 35 |
Virginia Natural Gas | 10 |  |  | 10 |
Chattanooga Gas | 7 |  |  | 2 |
Nicor Gas | 3 |  |  | 3 |
Total | $ | 43 |  |  | $ | 50 |

X
- Definition The entire disclosure for public utilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//980/tableOfContent + Details
Name: | us-gaap_PublicUtilitiesDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_RegulatedOperationsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration