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CONTINGENCIES, COMMITMENTS, AND GUARANTEES (Tables) | 12 Months Ended
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Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract] |
Schedule of regulatory liabilities | Details of regulatory assets and (liabilities) reflected in the balance sheets at December 31, 2024 and 2023 are provided in the following tables:
| Southern Company | Alabama Power | Georgia Power | Mississippi Power | Southern Company Gas
| (in millions)
At December 31, 2024 |  |  |  |  |
AROs(*) | $ | 5,810 |  | $ | 1,906 |  | $ | 3,658 |  | $ | 248 |  | $ | — |
Retiree benefit plans(*) | 2,605 |  | 680 |  | 892 |  | 134 |  | 44 |
Remaining net book value of retired assets | 1,198 |  | 454 |  | 729 |  | 15 |  | — |
Deferred income tax charges | 927 |  | 264 |  | 634 |  | 27 |  | — |
Storm damage | 859 |  | — |  | 827 |  | 32 |  | — |
Deferred depreciation | 535 |  | 286 |  | 249 |  | — |  | — |
Environmental remediation(*) | 249 |  | — |  | 16 |  | — |  | 233 |
Vacation pay(*) | 224 |  | 85 |  | 112 |  | 12 |  | 15 |
Loss on reacquired debt | 219 |  | 32 |  | 183 |  | 4 |  | — |
Software and cloud computing costs | 200 |  | 76 |  | 116 |  | 4 |  | 4 |
Under recovered regulatory clause revenues | 167 |  | 119 |  | — |  | 17 |  | 31 |
Regulatory clauses | 162 |  | 82 |  | — |  | — |  | 80 |
Nuclear outage | 92 |  | 39 |  | 53 |  | — |  | — |
Fuel-hedging (realized and unrealized) losses | 69 |  | 23 |  | 29 |  | 17 |  | — |
Qualifying repairs of natural gas distribution systems | 53 |  | — |  | — |  | — |  | 53 |
Long-term debt fair value adjustment | 52 |  | — |  | — |  | — |  | 52 |
Plant Daniel Units 3 and 4 | 23 |  | — |  | — |  | 23 |  | — |
Other regulatory assets | 184 |  | 42 |  | 40 |  | 30 |  | 72 |
Deferred income tax credits | (4,536) |  | (1,398) |  | (2,149) |  | (219) |  | (755) |
Other cost of removal obligations | (1,176) |  | 24 |  | 816 |  | (170) |  | (1,846) |
Over recovered regulatory clause revenues | (285) |  | (29) |  | (52) |  | — |  | (204) |
Reliability reserves | (188) |  | (131) |  | — |  | (57) |  | — |
Storm/property damage reserves | (122) |  | (70) |  | — |  | (52) |  | — |
Nuclear fuel disposal cost recovery | (100) |  | (100) |  | — |  | — |  | — |
Other regulatory liabilities | (180) |  | (28) |  | (14) |  | (6) |  | (31) |
Total regulatory assets (liabilities), net | $ | 7,041 |  | $ | 2,356 |  | $ | 6,139 |  | $ | 59 |  | $ | (2,252) |
| Southern Company | Alabama Power | Georgia Power | Mississippi Power | Southern Company Gas
| (in millions)
At December 31, 2023 |  |  |  |  |
AROs(*) | $ | 5,733 |  | $ | 1,936 |  | $ | 3,505 |  | $ | 247 |  | $ | — |
Retiree benefit plans(*) | 3,011 |  | 815 |  | 976 |  | 140 |  | 146 |
Remaining net book value of retired assets | 1,357 |  | 499 |  | 841 |  | 17 |  | — |
Deferred income tax charges | 897 |  | 262 |  | 605 |  | 28 |  | — |
Under recovered regulatory clause revenues | 413 |  | 381 |  | — |  | 12 |  | 20 |
Fuel-hedging (realized and unrealized) losses | 270 |  | 100 |  | 121 |  | 49 |  | — |
Deferred depreciation | 270 |  | 143 |  | 127 |  | — |  | — |
Environmental remediation(*) | 255 |  | — |  | 20 |  | — |  | 235 |
Loss on reacquired debt | 238 |  | 35 |  | 197 |  | 5 |  | 1 |
Vacation pay(*) | 217 |  | 83 |  | 107 |  | 11 |  | 16 |
Software and cloud computing costs | 150 |  | 59 |  | 84 |  | 2 |  | 5 |
Regulatory clauses | 140 |  | 112 |  | — |  | — |  | 28 |
Storm damage | 92 |  | — |  | 54 |  | 38 |  | — |
Nuclear outage | 83 |  | 50 |  | 33 |  | — |  | — |
Long-term debt fair value adjustment | 60 |  | — |  | — |  | — |  | 60 |
Qualifying repairs of natural gas distribution systems | 40 |  | — |  | — |  | — |  | 40 |
Plant Daniel Units 3 and 4 | 25 |  | — |  | — |  | 25 |  | — |
Other regulatory assets | 189 |  | 39 |  | 33 |  | 25 |  | 93 |
Deferred income tax credits | (4,686) |  | (1,506) |  | (2,161) |  | (241) |  | (759) |
Other cost of removal obligations | (1,312) |  | 28 |  | 617 |  | (186) |  | (1,771) |
Over recovered regulatory clause revenues | (287) |  | (3) |  | (46) |  | — |  | (238) |
Reliability reserves | (179) |  | (143) |  | — |  | (36) |  | — |
Storm/property damage reserves | (120) |  | (76) |  | — |  | (44) |  | — |
Other regulatory liabilities | (333) |  | (94) |  | (23) |  | (2) |  | (101) |
Total regulatory assets (liabilities), net | $ | 6,523 |  | $ | 2,720 |  | $ | 5,090 |  | $ | 90 |  | $ | (2,225) |
(*)Generally not earning a return as they are excluded from rate base or are offset in rate base by a corresponding asset or liability. 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: AROs and other cost of removal obligations – Generally recorded over the related property lives, which may range up to 64 years for Alabama Power, 54 years for Georgia Power, 67 years for Mississippi Power, and 85 years for Southern Company Gas. AROs and other 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. Retiree benefit plans – Recovered and amortized over the average remaining service period, which may range up to 14 years for Alabama Power, Georgia Power, Mississippi 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. Remaining net book value of retired assets – Alabama Power: Primarily represents the net book value of Plant Gorgas Unit 10 ($419 million at December 31, 2024) being amortized over 13 years (through 2037) and Plant Barry Unit 4 ($35 million at December 31, 2024) being amortized over 10 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 and Plant Hammond Units 3 and 4 (totaling $418 million and $302 million, respectively, at December 31, 2024) are being amortized over remaining periods between one and 11 years (between 2025 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 10 years (through 2033) and the wholesale portion is being amortized over 10 years (through 2034). See "Mississippi Power – Environmental Compliance Overview Plan" herein for additional information. Deferred income tax charges and credits – Charges are recovered and credits are primarily amortized over the related property lives, which may range up to 64 years for Alabama Power, 54 years for Georgia Power, 67 years for Mississippi Power, and 85 years for Southern Company Gas. See Note 10 for additional information. 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, 2024 include excess federal deferred income tax liabilities that are available for the benefit of customers in 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 at December 31, 2024 include $135 million of deferred income tax assets related to construction costs for Plant Vogtle Units 3 and 4 being recovered over 10 years (through 2034) and $102 million of excess state deferred income tax liabilities that will be returned to customers in 2025. See "Georgia Power – Nuclear Construction – Regulatory Matters" herein for additional information on recovery of costs related to Plant Vogtle Units 3 and 4. Southern Company Gas: Related amounts at December 31, 2024 include $24 million of deferred income tax liabilities being amortized over periods generally not exceeding five years, primarily related to excess state deferred income tax liabilities. See "Southern Company Gas – Rate Proceedings" herein for additional information. Storm damage – 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 seven years (through 2029). Deferred depreciation – Alabama Power: Represents deferred depreciation for Plant Barry Unit 5 ($114 million at December 31, 2024) and Plant Barry common coal assets ($48 million at December 31, 2024) to be amortized until 2036 beginning when Plant Barry Unit 5 is retired and Plant Gaston Unit 5 coal assets ($124 million at December 31, 2024) to be amortized until 2039 beginning when the assets are retired. Georgia Power: Represents deferred depreciation for Plant Scherer Units 1 through 3 ($139 million at December 31, 2024) to be amortized over six years beginning in 2029 and Plant Bowen Units 1 and 2 ($80 million at December 31, 2024) 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 ($29 million at December 31, 2024) being amortized over 10 years (through 2034). See "Georgia Power – Nuclear Construction – Regulatory Matters" herein for additional information on recovery of costs related to Plant Vogtle Units 3 and 4. Environmental remediation – 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. Vacation pay – Recorded as earned by employees and recovered as paid, generally within one year. Includes both vacation and banked holiday pay, if applicable. Loss on reacquired debt – Recovered over either the remaining life of the original issue or, if refinanced, over the remaining life of the new issue. At December 31, 2024, the remaining amortization periods do not exceed 23 years for Alabama Power, 28 years for Georgia Power, 17 years for Mississippi Power, and three years for Southern Company Gas. Software and cloud computing costs – 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). 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 following the completion of the projects and is expected to begin no earlier than 2026. For Southern Company Gas, costs are being amortized ratably over the life of the related software, which ranges up to 10 years (through 2034). Under and over recovered regulatory clause revenues – Alabama Power: Balances are recorded monthly and expected to be recovered over periods of up to six 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, 2024, $17 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. Regulatory clauses – 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. 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. Fuel-hedging (realized and unrealized) losses and gains – 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. Immaterial amounts for fuel-hedging gains at December 31, 2024 and 2023 are included in other regulatory liabilities. Qualifying repairs of natural gas distribution systems – Represents deferred costs of certain repairs at Atlanta Gas Light being amortized over 20 years. Long-term debt fair value adjustment – Recovered over the remaining lives of the original debt issuances at acquisition, which range up to 14 years at December 31, 2024. Plant Daniel Units 3 and 4 – 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, 2024, consists of the $16 million retail portion being amortized through 2039 over the remaining life of the related property and the $8 million wholesale portion being amortized over 10 years (through 2034). Other regulatory assets – Comprised of numerous immaterial components with remaining amortization periods at December 31, 2024 generally not exceeding 19 years for Alabama Power, 10 years for Georgia Power, 10 years for Mississippi Power, and 15 years for Southern Company Gas. Reliability reserves and storm/property damage reserves – 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. Nuclear fuel disposal cost recovery – Represents award resulting from litigation related to nuclear fuel disposal costs. See Note 3 under "Nuclear Fuel Disposal Costs" for additional information. Other regulatory liabilities – Comprised of numerous immaterial components with remaining amortization periods at December 31, 2024 generally not exceeding one year for Alabama Power, three years for Georgia Power, one year for Mississippi Power, and 20 years for Southern Company Gas. At December 31, 2024 and 2023, the environmental remediation liability and the balance of under recovered environmental remediation costs were reflected in the balance sheets of Southern Company, Georgia Power, and Southern Company Gas as shown in the table below. Alabama Power and Mississippi Power did not have environmental remediation liabilities at December 31, 2024 or 2023.
| Southern Company | Georgia Power | Southern Company Gas
| (in millions)
December 31, 2024: |  |  |
Environmental remediation liability: |  |  |
Other current liabilities | $ | 37 |  | $ | 13 |  | $ | 24 |
Accrued environmental remediation | 198 |  | — |  | 198 |
Under recovered environmental remediation costs: |  |  |
Other regulatory assets, current | $ | 37 |  | $ | 5 |  | $ | 32 |
Other regulatory assets, deferred | 212 |  | 11 |  | 201 |
December 31, 2023: |  |  |
Environmental remediation liability: |  |  |
Other current liabilities | $ | 44 |  | $ | 14 |  | $ | 30 |
Accrued environmental remediation | 192 |  | — |  | 192 |
Under recovered environmental remediation costs: |  |  |
Other regulatory assets, current | $ | 45 |  | $ | 5 |  | $ | 40 |
Other regulatory assets, deferred | 210 |  | 15 |  | 195 |

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