SOUTHERN CO

(D)REVENUE FROM CONTRACTS WITH CUSTOMERS AND LEASE INCOME

Revenue from Contracts with Customers

The Registrants generate revenues from a variety of sources, some of which are not accounted for as revenue from contracts with customers, such as leases, derivatives, and certain cost recovery mechanisms. Included in the wholesale electric revenues of the traditional electric operating companies and Southern Power are revenues associated with affiliate transactions. These revenues are generated through long-term PPAs or short-term energy sales made in accordance with the IIC, as approved by the FERC. Amounts related to these affiliate revenues are eliminated in consolidation for Southern Company. See Note 1 to the financial statements under "Revenues" and "Affiliate Transactions" in Item 8 of the Form 10-K for additional information. See "Lease Income" herein and Note (J) for additional information on revenue accounted for under lease and derivative accounting guidance, respectively.

The following table disaggregates revenue from contracts with customers for the three months ended March 31, 2024 and 2023:

(*)Other revenue sources relate to revenues from customers accounted for as derivatives and leases, alternative revenue programs at Southern Company Gas, and cost recovery mechanisms and revenues (including those related to fuel costs) that meet other scope exceptions for revenues from contracts with customers at the traditional electric operating companies.

Contract Balances

The following table reflects the closing balances of receivables, contract assets, and contract liabilities related to revenues from contracts with customers at March 31, 2024 and December 31, 2023:

Contract assets for Georgia Power primarily relate to retail customer fixed bill programs, where the payment is contingent upon Georgia Power's continued performance and the customer's continued participation in the program over aone-year contract term, and unregulated service agreements, where payment is contingent on project completion. Contract liabilities for Georgia Power primarily relate to cash collections recognized in advance of revenue for unregulated service agreements. Southern Company Gas' contract assets relate to work performed on an energy efficiency enhancement and upgrade contract with the U.S. General Services Administration. Southern Company Gas receives cash advances from a third-party financial institution to fund work performed, of which approximately $65 million had been received at March 31, 2024. These advances have been accounted for as long-term debt on the balance sheets. See Note 1 to the financial statements under "Affiliate Transactions" in Item 8 of the Form 10-K for additional information regarding the construction contract. At March 31, 2024 and December 31, 2023, Southern Company's unregulated distributed generation business had contract assets of $108 million and $91 million, respectively, and contract liabilities of $188 million and $115 million, respectively, for outstanding performance obligations, all of which are expected to be satisfied within one year.

Revenues recognized in the three months ended March 31, 2024, which were included in contract liabilities at December 31, 2023, were $28 million for Southern Company andimmaterial for the other Registrants. Contract liabilities are primarily classified as current on the balance sheets as the corresponding revenues are generally expected to be recognized within one year.

Remaining Performance Obligations

Southern Company's subsidiaries may enter into long-term contracts with customers in which revenues are recognized as performance obligations are satisfied over the contract term. For the traditional electric operating companies and Southern Power, these contracts primarily relate to PPAs whereby electricity and generation capacity are provided to a customer. The revenue recognized for the delivery of electricity is variable; however, certain PPAs include a fixed payment for fixed generation capacity over the term of the contract. For Southern Company Gas, these contracts primarily relate to the U.S. General Services Administration contract described above. Southern Company's unregulated distributed generation business also has partially satisfied performance obligations related to certain fixed price contracts. Revenues from contracts with customers related to these performance obligations remaining at March 31, 2024 are expected to be recognized as follows:

(*)Includes performance obligations related to affiliate PPAs with Georgia Power. See Note 1 to the financial statements under "Affiliate Transactions" in Item 8 of the Form 10-K for additional information.

Lease Income

Lease income for the three months ended March 31, 2024 and 2023 is as follows:

Lease payments received under tolling arrangements and PPAs consist of either scheduled payments or variable payments based on the amount of energy produced by the underlying electric generating units. Lease income related to PPAs for Alabama Power and Southern Power is included in wholesale revenues.