CENTURY ALUMINUM CO

a. Evaluation of Disclosure Controls and Procedures

As of June 30, 2024, we carried out an evaluation, under the supervision and with the participation of our management, including our Chief Executive Officer and Principal Financial Officer, of the effectiveness of our disclosure controls and procedures. Based upon that evaluation, our management, including the Chief Executive Officer and Principal Financial Officer, concluded that our disclosure controls and procedures were effective as of June 30, 2024.

b. Changes in Internal Control over Financial Reporting

On May 2, 2023, our wholly-owned subsidiary, Century Aluminum Jamaica Holdings, Inc. ("CAJH"), completed the acquisition of all the outstanding share capital of General Alumina Holdings Limited ("GAHL"), the indirect holder of a 55% interest in Jamalco, an unincorporated joint venture engaged in bauxite mining and alumina production in Jamaica. We have implemented internal controls over significant processes specific to Jamalco that management believes are appropriate in consideration of related integration of operations, systems, and control activities. Except as described in preceding sentence relating to integration of internal controls specific to Jamalco, as of June 30, 2024 there were no material changes in our internal control over financial reporting.