KALU Kaiser Aluminum Corporation

Class I Directors – Term Expiring at the 2025 Annual Meeting

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Proposal 2 - Advisory Vote to Approve Named Executive Officer Compensation

In accordance with the Dodd-Frank Wall Street Reform and Consumer Protection Act, or the Dodd-Frank Act, and Section 14A of the Securities Exchange Act of 1934, referred to herein as the Exchange Act, we ask stockholders to vote annually on a non-binding, advisory resolution to approve our named executive officer compensation. The vote is not intended to address any specific component of our executive compensation program, but rather the overall compensation of our named executive officers as described in this Proxy Statement. The text of the resolution is as follows:

RESOLVED, that the compensation paid to the named executive officers of Kaiser Aluminum Corporation, as described in the proxy statement for the company's 2023 annual meeting of stockholders pursuant to Item 402 of Regulation S-K (which disclosure includes the "Executive Compensation - Compensation Discussion and Analysis" section and the Summary Compensation Table and other compensation tables and related narrative discussions), is hereby APPROVED.

The compensation committee, based on our management's recommendation, did not make any adjustments to our existing incentive programs despite the numerous challenges we encountered in 2022, including unprecedented supply chain disruptions, inflationary cost pressures and historically high labor turnover, which negatively impacted our financial performance and resulted in no payout under our 2022 short-term incentive plan and no performance shares earned under our 2020 – 2022 long-term incentive plan. Our incentive programs are designed to “pay for performance,” and it is expected that payouts may be impacted during difficult business/economic conditions. Accordingly, we determined that it was appropriate to maintain our existing incentive programs without adjustments that would otherwise mitigate the impact of the challenges we experienced on the payouts under our incentive plans.

As described in further detail in the CD&A section, our compensation structure was developed to achieve the following objectives, which we believe are critical for enhancing stockholder value and our long-term success and sustainability:

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The compensation committee reviewed our compensation program for 2022. The review included consideration of stockholder feedback, the approximately 96% approval of the 2022 advisory vote to approve our named executive officer compensation, and discussions with Meridian and management regarding existing and contemplated market practices, as well as the structure and objectives of each component of our compensation. Upon completion of that review, the compensation committee determined that the compensation of our named executive officers in 2022 would consist primarily of the following components:

Our board's compensation committee, working with the compensation committee’s independent compensation consultant, Meridian Compensation Partners, LLC (referred to herein as Meridian), reviews, evaluates and updates our compensation peer group, which includes companies in both similar and different industries, at least annually. For 2022, the compensation committee approved a new 26-company peer group more fully described in our CD&A section to account for the increased company size and scope resulting from the acquisition of Warrick. As of November 2021, the new custom peer group had (1) market capitalization ranging from approximately $696 million to approximately $12.9 billion and a median market capitalization of approximately $3.4 billion, and (2) trailing 12 months revenues ranging from $1.5 billion to approximately $6.8 billion and median revenue of approximately $3.4 billion. Our market capitalization and revenue, both as of December 31, 2022, were $1.2 billion and $3.4 billion, respectively. Due to the differences in size among the companies in our peer group, Meridian uses a regression analysis to adjust survey data results based on our revenue as compared to the revenue of other companies in our peer group.

We no longer maintain a defined benefit pension plan or retiree medical program that covers members of senior management. Retirement benefits to our senior management, including our named executive officers, are provided through a defined contribution retirement program consisting of a 401(k) plan (which we refer to as our Savings Plan) and a nonqualified and unsecured deferred compensation plan (which we refer to as our Restoration Plan) intended to restore benefits that would be payable to designated participants in our Savings Plan but for the limitations on benefit accruals and payments imposed by the Internal Revenue Code of 1986, as amended (referred herein as the Code).

For 2022, over 80% of the target total compensation of our CEO and approximately 55% to 70% of the target total compensation of our other named executive officers, consisted of at-risk compensation, which we define as compensation that either (1) will be realized, if at all, only if certain financial performance levels are achieved as in the case of our annual short-term incentive and the portion of our long-term incentive consisting of performance shares or (2) is time-based as in the case of the portion of our long-term incentive compensation consisting of restricted stock units.

Our compensation structure also supports our corporate governance practices, which further align the interests of senior management and our stockholders. The table below sets forth the best practice compensation features we have adopted as of 2022.

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We believe our incentive compensation programs are designed to demand continuous improvement. We also believe that design emphasizing the importance of successful execution of each of our six key strategic initiatives is important to our long-term success and aligns the interests of our named executive officers with our stockholders. Our key strategic initiatives are to:

We urge our stockholders to review our CD&A which describes our compensation philosophy and programs in detail and to approve the compensation of our named executive officers. While this vote to approve our named executive officer compensation is non-binding and solely advisory in nature, our board of directors and the compensation committee value the opinions of our stockholders and expect to consider the outcome of the vote when determining future executive compensation programs. We hold this advisory vote to approve our named executive officer compensation on an annual basis, and the next such vote is expected to be conducted at our 2024 annual meeting.

The board of directors recommends a vote "FOR" the approval, on a non-binding, advisory basis, of the compensation of our named executive officers as disclosed in this Proxy Statement.

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Proposal 3 – Advisory Vote on the Frequency of Future Advisory Votes to Approve Named Executive Officer Compensation

In accordance with the Dodd-Frank Act and Section 14A of the Exchange Act, we ask stockholders to vote once every six years on an advisory, non-binding resolution regarding the frequency of future advisory votes to approve named executive compensation. The vote is intended to obtain the recommendation of stockholders as to whether an advisory vote to approve the compensation of our named executive officers should occur every one, two, or three years. Stockholders may also abstain with respect to this proposal.

After careful consideration of this proposal, our board of directors has determined that an annual advisory vote to approve the compensation of our named executive officers is the most appropriate alternative for our company. We believe that an annual advisory vote to approve named executive officer compensation will (1) allow us to obtain information on stockholders’ views on executive compensation on a more consistent basis, (2) provide our board of directors and compensation committee with frequent input from stockholders on executive compensation, and (3) advance our policy of seeking input from, and engaging in discussions with, our stockholders on corporate governance matters and our executive compensation philosophy, policies and practices. Accordingly, our board of directors recommends the submission to our stockholders of an advisory vote to approve named executive officer compensation on an annual basis.

While this vote on the frequency of future advisory votes to approve named executive officer compensation is non-binding and solely advisory in nature, our board of directors and the compensation committee value the opinions that our stockholders express in their votes and will consider the outcome of the vote when determining the frequency of future advisory votes to approve the compensation of our named executive officers. The next frequency vote is expected to occur at the 2029 annual meeting.

The board of directors recommends a vote for the option of “EVERY 1 YEAR” as the frequency of future advisory votes on the compensation of our named executive officers. In accordance with the Dodd-Frank Act and Section 14A of the Exchange Act, we ask stockholders to vote once every six years on an advisory, non-binding resolution regarding the frequency of future advisory votes to approve named executive compensation. The vote is intended to obtain the recommendation of stockholders as to whether an advisory vote to approve the compensation of our named executive officers should occur every one, two, or three years. Stockholders may also abstain with respect to this proposal.

The board of directors recommends a vote for the option of “EVERY 1 YEAR” as the frequency of future advisory votes on the compensation of our named executive officers.

Proposal 4 - Ratification of the Selection of our Independent Registered Public Accounting Firm

Pursuant to the audit committee charter, the audit committee has the sole authority to retain an independent registered public accounting firm for our company. The board of directors requests that the stockholders ratify the audit committee's selection of Deloitte & Touche LLP as our independent registered public accounting firm for 2023.

The audit committee will not be bound by the ratification of, or failure to ratify, the selection of Deloitte & Touche LLP, but the audit committee will consider any failure to ratify the selection of Deloitte & Touche LLP in connection with the appointment of our independent registered public accounting firm for 2024.

The board of directors recommends a vote "FOR" the ratification of the audit committee's selection of Deloitte & Touche LLP as our independent registered public accounting firm for 2023.

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CORPORATE GOVERNANCE

Our board of directors is responsible for providing effective governance over the affairs of our company. Our corporate governance practices are designed to align the interests of our board of directors and management with those of our stockholders and to promote honesty, integrity and our corporate values throughout the company. Highlights of our corporate governance practices are described below.

A copy of the current charter, as approved by our board of directors, for each of the executive committee, audit committee, compensation committee, nominating and corporate governance committee and ESG committee, and a copy of each of our corporate governance guidelines and our code of business conduct and ethics, which applies to all of our directors and employees, including our executive officers, are available on our website at www.kaiseraluminum.com under "Investors - Governance." Furthermore, we will post any amendments to our code of business conduct and ethics, or waivers of the code for our directors or executive officers, on our website at www.kaiseraluminum.com under "Investors- Governance."

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Board Leadership Structure

In July 2020, in connection with Mr. Harvey’s succession as CEO, we separated the roles of CEO and Chairman of the Board of our company and Mr. Hockema, our former CEO, became Executive Chairman of the Board. Dr. Osborne currently serves as our Lead Independent Director, and, in connection with our board leadership succession planning, the board of directors has approved the transition of the Lead Independent Director position to Mr. Arnold, which will be effective following the Annual Meeting. We believe that Mr. Hockema's substantial experience with our company and in the metals industries, the independence of the other directors, our governance structure and the interaction between and among Messrs. Hockema, Harvey, Osborne and Arnold and the other directors make our board leadership structure the most appropriate for our company and our stockholders.

Our corporate governance guidelines and governance structure require a Lead Independent Director to be selected by a majority of the independent directors when the Executive Chairman of the board is not independent, thereby ensuring that there is independent leadership within our board of directors and allowing our independent directors to function as a body distinct from management and evaluate the performance of Mr. Harvey and our management independently and objectively. The responsibilities of our Lead Independent Director include:

Each of the audit, compensation, ESG and nominating and corporate governance committees consists solely of independent directors. The chair of each committee serves as a liaison to keep our full board of directors and our CEO apprised of the work performed by their respective committees at each of our regularly scheduled board meetings and as otherwise required. Finally, under our bylaws, special meetings of our board of directors may be called by the Chairman, our CEO or a majority of our board members.

Under our corporate governance guidelines, each member of our board of directors may submit items to be included on the agenda for any meeting of our board of directors and raise topics that are not on the agenda at any meeting of our board of directors. In addition, our independent directors, representing nine of our 11 directors, are required to meet at least quarterly in executive sessions at which only independent directors are present. Additionally, we encourage direct communication among our directors and with our CEO before, during and after formal board and committee meetings and facilitate those communications around all of our meetings. Our directors also have full access to our officers, employees and advisors.

Risk Oversight

We have policies in place to identify, assess and manage potential risks and to continually review the procedures that we have designed and implemented to mitigate those risks. We believe that our board of directors provides effective oversight of the risk management function. Under its charter, the audit committee of our board of directors is responsible for discussing our risk management policies, including, without limitation, the steps taken and to be taken to monitor and control our major financial risk exposures. The compensation committee of our board of directors is responsible for assessing risks associated with our compensation policies and incentivizing the conduct of our business in a manner consistent with our corporate values and implementing our clawback policies. The ESG committee of our board of directors is responsible for overseeing our ESG risks, including overseeing our overall approach to ESG principles and related disclosures, reviewing and evaluating the succession planning of our executive officers (other than the CEO), and reviewing the diversity of our management and workforce and our approach to diversity, equity and inclusion. Our Executive Vice President, Chief Administrative Officer and

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General Counsel, working with a committee of other members of senior management, oversees our climate-related risk management approach, and we report regularly to the ESG committee and the full board of directors.

In addition, our full board of directors is actively engaged in the review and assessment of our risk management policies, conducts a comprehensive review at least annually during a regularly scheduled board meeting and routinely requests that specific risk-related items be included on board and committee meeting agendas. We also engage in an ongoing enterprise risk management process pursuant to which we formally identify, categorize and assess our risks and risk mitigation strategies and routinely update the audit committee and the full board of directors regarding this process.

Information Security

We employ information systems to support our business. As is the case for other manufacturing companies of comparable size and scope, we, from time to time, experience attempted cyber-attacks on our information system. We also face risks associated with other potential significant failures or disruptions of our information technology networks. We utilize a risk-based, multi-layered information security approach following the National Institute of Standards and Technology Cybersecurity Framework and have adopted and implemented an approach to identify and mitigate information security risks that we believe is commercially reasonable for manufacturing companies of our size and scope, including many of the best practices of the National Institute of Standards and Technology Cybersecurity Framework.

Our Director - Kaiser Protect is responsible for overseeing our cybersecurity program across our company and reports directly to our Chief Information Officer (“CIO”), who is responsible for the usability, implementation and management of our information and computing systems. At least monthly, our senior management reviews our information security performance and recent cybersecurity industry trends and risks with our CIO and Director - Kaiser Protect, Management also reports these updates to the audit committee at least twice a year with two of such reports reviewed with the full board of directors. The audit committee is responsible for the review of risks relating to our information technology system, including cybersecurity, emerging cybersecurity developments and threats and our strategy for mitigating cybersecurity risks. Our entire board of directors is responsible for overseeing management’s risk assessment and risk management processes designed to monitor and mitigate information security risks.

We regularly engage independent third parties to test our information security processes and systems as part of our overall enterprise risk management. We also periodically engage in tabletop exercises with third-party consultants to better prepare us for potential cyber threats. In addition, we conduct annual information security training to ensure employees are aware of information security risks and to enable them to take steps to mitigate those risks. As part of this program, we also take reasonable steps to ensure our executive management and employees who may come into possession of confidential financial information receive appropriate information security awareness training.

We have not experienced a material information security breach. In addition, to date, no attempted cyber-attack or other attempted intrusion on our information technology networks has resulted in a material adverse impact on our operations or financial results, or in any penalties or settlements. In the event an attack or other intrusion were to be successful, we have a response team of internal and external resources engaged and prepared to respond. We also have a cyber risk insurance policy to help us mitigate risk exposure by offsetting costs involved with recovery and remediation in the event of a successful attack or other intrusion.

Director Independence

Our corporate governance guidelines require that a majority of the members of our board of directors satisfy the independence requirements set forth in the rules of the Nasdaq Stock Market. We refer to these requirements as the general independence criteria. Additionally, the audit committee charter, compensation committee charter and nominating and corporate governance committee charter require that all respective committee members satisfy the general independence criteria. There are no family relationships among our officers or directors.

Based upon information requested from and provided by our directors concerning their backgrounds, employment and affiliations, including family relationships, our board of directors has determined that each of Mmes. Martin and Sebastian and Messrs. Arnold, Foster, Grimley Osborne, Stebbins, Wilcox and Williams, representing nine of our 11 directors, satisfies the general independence criteria. The two remaining directors, Messrs. Harvey and Hockema, do not meet the independence criteria as our CEO and former CEO, respectively. In making such determination, our board of directors considered the relationships that each of our directors have with our company and all other facts and circumstances our

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board of directors deemed relevant in determining the independence of each of our directors in accordance with the general independence criteria.

Director Designation Agreement

On July 6, 2006, we entered into a Director Designation Agreement with the USW under which the USW has certain rights to designate board candidates for nomination. We believe that:

Accordingly, in connection with the renewal and ratification of a new five-year collective bargaining agreement with members of the USW at our Spokane, Washington and Newark, Ohio facilities, in December 2019, the Director Designation Agreement which was set to expire on December 31, 2020 was extended to December 31, 2025. Under the Director Designation Agreement, as amended, the USW generally has the right to designate for nomination the minimum number of director candidates necessary to ensure that, assuming the nominated candidates are elected by our stockholders, at least 40% of the members of our board of directors have been nominated by the USW.

The Director Designation Agreement contains requirements as to the timeliness, form and substance of the notice the USW must give to the nominating and corporate governance committee in order to nominate candidates. The nominating and corporate governance committee is required to determine in good faith whether each properly submitted candidate satisfies the qualifications set forth in the Director Designation Agreement. Pursuant to the terms of the Director Designation Agreement, if the nominating and corporate governance committee determines that a nominated candidate satisfies the qualifications, the committee will, unless otherwise required by its fiduciary duties, recommend the candidate to our board of directors for inclusion in the slate of directors to be recommended by the board of directors in our proxy statement. Similarly, the board of directors will, unless otherwise required by its fiduciary duties, accept the designation for nomination and include the candidate in the slate of directors that the board of directors recommends. Notwithstanding the foregoing, the USW may not nominate an incumbent candidate without our approval.

In addition, the Director Designation Agreement provides that, so long as our board of directors maintains an audit committee, executive committee or nominating and corporate governance committee, each of these committees will, unless otherwise required by the fiduciary duties of our board of directors, include at least one director nominated by the USW (provided at least one director nominated by the USW is qualified to serve on the applicable committee as determined in good faith by our board of directors). Current members of our board of directors that have been nominated by the USW are Messrs. Foster, Grimley and Wilcox and Ms. Sebastian.

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Executive Committee

The executive committee of our board of directors manages our business and affairs requiring attention prior to the next regular meeting of our board of directors. However, the executive committee does not have the power to (1) approve or adopt, or recommend to our stockholders, any action or matter expressly required by law to be submitted to our stockholders for approval, (2) adopt, amend or repeal the bylaws of our company, or (3) take any other action reserved for action by our

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board of directors pursuant to a resolution of our board of directors or otherwise prohibited to be taken by the executive committee by law or pursuant to our amended and restated certificate of incorporation or bylaws.

The executive committee charter requires that a majority of the members of the executive committee satisfy the general independence criteria. In addition, the members of the executive committee must include the chairman of our board of directors and at least one of the directors nominated by the USW. The executive committee is currently comprised of our CEO, executive chairman of the board of directors, lead independent director and the chair of each of the other standing committees of the board of directors.

Audit Committee

The audit committee of our board of directors oversees our accounting and financial reporting practices and processes and the audit of our financial statements on behalf of our board of directors. The audit committee is responsible for appointing, compensating, retaining and overseeing the work of our independent accounting firm. Other duties and responsibilities of the audit committee include:

The audit committee charter requires that all members of the audit committee satisfy the general independence criteria. The charter also requires that no audit committee members may have participated in the preparation of our financial statements during the three years prior to their appointment as a member and that each audit committee member be able to read and understand fundamental financial statements, including a balance sheet, an income statement and a cash flow statement. Additionally, at least one member of the audit committee must have had past employment experience in finance or accounting, requisite professional certification in accounting or any other comparable experience which results in that individual's financial sophistication, including being or having been a chief executive officer, chief financial officer or other senior officer with financial oversight responsibilities, and that member or another member must have sufficient education or experience to have acquired the attributes necessary to meet the criteria of an "audit committee financial expert," as that term is defined in the rules promulgated by the Securities and Exchange Commission. In addition, the members of the audit committee must include at least one of the directors nominated by the USW so long as at least one director nominated by the USW is appropriately qualified.

Our board of directors has determined that all members of the audit committee during 2022 (1) meet the general independence criteria, the heightened independence criteria for members of the audit committee set forth in the rules of the Nasdaq Stock Market and the criteria for independence set forth in Rule 10A-3(b)(1) under the Exchange Act, and (2) are able to read and understand fundamental financial statements. Our board of directors has also determined that no member of the audit committee participated in the preparation of our financial statements during the three years prior to their appointment as members of the committee. Finally, our board of directors has determined that each member of the audit committee satisfies the financial sophistication criteria described above and satisfies the criteria necessary to serve as the "audit committee financial expert," in each case based on his or her experience described in "Proposals Requiring Your Vote - Proposal 1 - Election of Directors" above.

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Compensation Committee

General

The compensation committee of our board of directors establishes and administers our policies, programs and procedures for compensating our senior management, including determining and approving the compensation of our executive officers. Other duties and responsibilities of the compensation committee include:

The compensation committee solicits the views of our CEO on compensation matters, including as they relate to our compensation of our executive officers and other members of senior management, including those reporting to our CEO. The compensation committee has retained Meridian to advise the compensation committee on all matters related to compensation of our CEO and other members of senior management. The compensation committee has reviewed the factors that could affect, and has assessed, Meridian's independence. Based on this review, the compensation committee has determined there are no conflicts of interest that have been raised by Meridian's work.

Meridian's services include (1) providing competitive market data and related assessments of executive compensation as background against which the compensation committee considers executive compensation, (2) preparing and reviewing tally and compensation summary sheets for our named executive officers, (3) apprising the compensation committee of trends and best practices associated with executive and director compensation, (4) providing support with respect to legal, regulatory and accounting considerations impacting compensation and benefit programs, (5) the development and review of a list of compensation peer group companies, and (6) attending meetings of the compensation committee and our board of directors when requested. These services are typically directed by the compensation committee and coordinated with our human resources and legal departments.

The compensation committee charter requires that all members of the compensation committee satisfy the general independence criteria and the heightened independence criteria for members of the compensation committee set forth in the rules of the Nasdaq Stock Market, as well as qualify as "non-employee directors" within the meaning of Rule 16b-3 promulgated under the Exchange Act. Our board of directors has determined that all members of the compensation committee during 2022 meet the applicable independence criteria.

The compensation committee may create one or more subcommittees, each subcommittee to consist of one or more members of the committee, and may delegate to the subcommittee any or all of the powers and authority of the committee.