CENTURY ALUMINUM CO

Disclosure Controls and Procedures

As of December 31, 2023, we carried out an evaluation, under the supervision and with the participation of our management, including our Chief Executive Officer and Chief Financial Officer, of the effectiveness of our disclosure controls and procedures. Based upon that evaluation, our management, including the Chief Executive Officer and Chief Financial Officer, concluded that our disclosure controls and procedures were ineffective as of December 31, 2023, because of a material weakness in internal controls over financial reporting described in Management’s Annual Report on Internal Control Over Financial Reporting below. Notwithstanding the material weakness, management believes the consolidated financial statements included in this Annual Report on Form 10-K present fairly, in all material respects, the Company’s financial condition, results of operations and cash flows as of and for the periods presented in accordance with U.S. GAAP.

Management's Report on Internal Control over Financial Reporting

Management is responsible for establishing and maintaining an adequate system of internal control over financial reporting for the Company. This system is designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. Because of its inherent limitations, a system of internal control over financial reporting can provide only reasonable assurance and may not prevent or detect misstatements. Further, because of changes in conditions, effectiveness of internal control over financial reporting may vary over time. Our system of internal control contains self-monitoring mechanisms, and actions are taken to correct deficiencies as they are identified.

As required by Section 404 of the Sarbanes-Oxley Act, management conducted an evaluation of the effectiveness of the system of internal control over financial reporting for the year ended December 31, 2023. Management’s evaluation was based on the framework in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations (COSO) of the Treadway Commission. As permitted by applicable SEC guidance, the scope of our assessment of internal control over financial reporting for fiscal year 2023 excluded internal controls over financial reporting of General Alumina Holdings Limited, the holder of a 55% interest in Jamalco JV ("Jamalco"), which was acquired on May 2, 2023. Jamalco constituted approximately 24.1% of the Company's total assets as of December 31, 2023 and approximately 6.9% of the Company's net sales for the year ended December 31, 2023. Based on this evaluation, management concluded that our system of internal control over financial reporting was effective as of December 31, 2023.

Material Weakness in Internal Control

As of December 31, 2023, our management has identified a deficiency in the design of internal control over financial reporting related to the application of purchase accounting to our acquisition of Jamalco. The design deficiency is a material weakness related to the review of the Company's allocation of excess fair value acquired between non-controlling interest and preliminary deferred bargain purchase gain.

Notwithstanding the material weakness, management believes the consolidated financial statements included in this Annual Report on Form 10-K present fairly, in all material respects, the Company’s financial condition, results of operations and cash flows as of and for the periods presented in accordance with U.S. GAAP.

The effectiveness of our internal control over financial reporting has been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their report which appears in Part II, Item 8 of this Annual Report on Form 10-K.

Remediation Plan for Material Weakness

Our management is committed to maintaining a strong internal control environment. In response to the identified material weakness above, management, with the oversight of the Audit Committee of the Board of Directors, took comprehensive actions to remediate the material weakness in internal control over financial reporting in the first quarter of 2024 in conjunction with the filing of this Annual Report on Form 10-K. We have changed the design of our internal controls over financial reporting to include a review of the allocation of the excess fair value of the net assets acquired at an entity level.

The remediation efforts are intended both to address the identified material weakness and to enhance our overall financial control environment on any future acquisitions of a similar nature. As management continues to finalize purchase accounting, no later than one year following the acquisition date or May 2, 2024, we may take additional measures to address this control deficiency or modify certain remediation measures described above.

Changes in Internal Control over Financial Reporting

On May 2, 2023, our wholly-owned subsidiary, Century Aluminum Jamaica Holdings, Inc., completed the acquisition of all the outstanding share capital of General Alumina Holdings Limited, the holder of a 55% interest in Jamalco JV ("Jamalco"), an unincorporated joint venture engaged in bauxite mining and alumina production in Jamaica. As a result of this acquisition, we are reviewing the internal controls of the acquired entities and making appropriate changes as deemed necessary. Except for the internal controls implemented in connection with our purchase accounting related to our acquisition of the acquired entities and the associated material weakness referred to above, during the three months ended December 31, 2023, there were no changes in our internal control over financial reporting that materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.