Employee Benefits

12 Months Ended

Dec. 31, 2024

Retirement Benefits [Abstract]

Employee Benefits

5. Employee Benefits

Defined Contribution Plans

We sponsor defined contribution 401(k) savings plans for certain hourly and salaried employees. Employees may contribute a portion of their compensation to the plans, and we match a specified percentage of these contributions in equivalent form of the investments elected by the employee. In addition, we make fixed annual contributions for certain hourly and salaried employees in varying amounts depending on hire date.

Deferred Compensation Plan

We sponsor a non-qualified, unfunded, unsecured plan of deferred compensation for certain employees who would otherwise suffer a loss of benefits under our defined contribution plan as a result of the limitations imposed by the Internal Revenue Code of 1986. Despite the plan being an unfunded plan, we make an annual contribution to a rabbi trust to fulfill future funding obligations, as contemplated by the terms of the plan. The assets in the trust are held in various investment funds at certain registered investment companies (see discussion below in “Fair Value of Plan Assets”) and are at all times subject to the claims of our general creditors. No participant has a claim to any assets of the trust; however, participants are eligible to receive distributions from the trust subject to vesting and other eligibility requirements. Offsetting liabilities relating to the deferred compensation plan are included within Other accrued liabilities and Long-term liabilities. Assets in the trust are accounted for as equity investments with changes in fair value recorded within Other income, net (see Note 13).

Other Benefits

We provide other benefits for certain members of senior management, including certain of our named executive officers, related to terminations of employment in specified circumstances, including in connection with a change in control, by us without cause and by the executive officer with good reason.

Defined Benefit Plans

Pension. We sponsor defined benefit pension plans for certain hourly bargaining unit employees and salaried employees. Pension benefits generally depend on length of service, job grade, and remuneration. Substantially all benefits are paid through pension trusts that are sufficiently funded to ensure that all plans can pay benefits to retirees as they become due. We use a December 31 measurement date for our pension plans.

OPEB. We sponsor an OPEB plan covering certain eligible retirees. Generally, the medical plans are unfunded and pay a percentage of medical expenses, reduced by deductibles and other coverage. Life insurance benefits are generally provided by insurance contracts. We use a December 31 measurement date for our OPEB plan.

Salaried VEBA Postretirement Obligation. Certain retirees who retired prior to 2004 and certain employees who were hired prior to February 2002 and have subsequently retired or will retire with the requisite age and service, along with their surviving spouses and eligible

dependents, are eligible to participate in a Salaried VEBA. The accumulated postretirement benefit obligation (“APBO”) for the Salaried VEBA was computed based on the level of benefits being provided. Since the Salaried VEBA pays out a fixed annual amount to its participants, no future cost trend rate increase was assumed in computing the APBO for the Salaried VEBA.

We have an ongoing obligation with no express termination date to make variable cash contributions up to a maximum of $2.9 million annually to the Salaried VEBA. The Salaried VEBA assets are invested in various managed funds based on information we received from the trustee of the Salaried VEBA. Our variable payment, if any, is treated as a funding/contribution policy and not counted as a Salaried VEBA asset at the accrual date for actuarial purposes. We determined that in the first quarter of 2025 we will pay approximately $0.7 million with respect to 2024. During the first quarter of 2024, we paid $1.1 million with respect to 2023. Such amounts were recorded within Other accrued liabilities (see Note 2). We account for the Salaried VEBA as a defined benefit plan in our financial statements using a December 31 measurement date.

Key Assumptions. The following table presents the weighted average assumptions used to determine benefit obligations:

	Pension Plans1						OPEB						Salaried VEBA
	As of December 31,						As of December 31,						As of December 31,
	2024			2023			2024			2023			2024			2023
Discount rate		5.54	%		4.95	%		5.48	%		4.92	%		5.40	%		4.89	%
Rate of compensation increase		2.56	%		2.63	%		—	%		—	%		—	%		—	%

1.Assumptions for our pension plans are weighted based on the total benefit obligations of each.

The following table presents the weighted average assumptions used to determine net periodic postretirement and postemployment benefit cost:

	Pension Plans1									OPEB									Salaried VEBA
	Year Ended December 31,									Year Ended December 31,									Year Ended December 31,
	2024			2023			2022			2024			2023			2022			2024			2023			2022
Discount rate		5.00	%		5.19	%		2.90	%		4.92	%		5.14	%		2.64	%		4.89	%		5.10	%		2.49	%
Expected long-term return on plan assets2		6.31	%		6.33	%		6.02	%		—	%		—	%		—	%		5.75	%		5.75	%		5.50	%
Rate of compensation increase		2.56	%		2.63	%		2.69	%		—	%		—	%		—	%		—	%		—	%		—	%

1.Assumptions for our pension plans are weighted based on the total benefit obligations of each.

2.The expected long-term rate of return assumption for the Salaried VEBA is based on the targeted investment portfolios provided to us by the trustee of the Salaried VEBA.

In measuring the expected cost of benefits covered by our OPEB plan, we estimate a healthcare cost trend rate representing the annual rates of change in the costs of the healthcare benefits currently provided by the OPEB plan. The 2024 actuarial valuation assumed a 7.7% annual rate of increase in the per capita cost of covered healthcare claims with the rate decreasing until reaching 4.5% in 2038.

Benefit Obligations and Funded Status. The following table presents the benefit obligations and funded status of our pension plans, OPEB, and the Salaried VEBA and the corresponding amounts that are included in our Consolidated Balance Sheets (in millions of dollars):

	Pension Plans						OPEB						Salaried VEBA
	As of December 31,						As of December 31,						As of December 31,
	2024			2023			2024			2023			2024			2023
Change in benefit obligation:
Obligation at beginning of year	$	30.5		$	18.8		$	68.8		$	66.4		$	46.9		$	58.9
Foreign currency translation adjustment		(0.5	)		0.2			—			—			—			—
Service cost		3.6			3.8			1.1			1.1			—			—
Interest cost		1.6			1.3			3.3			3.4			2.2			2.9
Prior service cost (credit)1		2.2			6.6			—			—			—			(8.8	)
Actuarial (gain) loss2		(1.6	)		0.2			(6.8	)		(0.7	)		(1.4	)		0.4
Plan participants contributions		0.1			0.1			0.2			0.1			—			—
Benefits paid		(0.7	)		(0.5	)		(1.9	)		(1.5	)		(4.8	)		(6.5	)
Settlements3		(4.5	)		—			—			—			—			—
Obligation at end of year4		30.7			30.5			64.7			68.8			42.9			46.9
Change in plan assets:
Fair market value of plan assets at beginning of year		20.5			14.9			—			—			43.1			42.4
Foreign currency translation adjustment		0.3			0.2			—			—			—			—
Actual return on assets		0.9			1.4			—			—			3.9			6.1
Plan participants contributions		0.1			0.1			0.2			0.1			—			—
Company contributions		5.9			4.4			1.7			1.4			0.7			1.1
Benefits paid		(0.7	)		(0.5	)		(1.9	)		(1.5	)		(4.8	)		(6.5	)
Settlements3		(4.5	)		—			—			—			—			—
Fair market value of plan assets at end of year		22.5			20.5			—			—			42.9			43.1
Net funded status5	$	(8.2	)	$	(10.0	)	$	(64.7	)	$	(68.8	)	$	—		$	(3.8	)
Cumulative gain (loss) recognized in Accumulated other comprehensive income:
Accumulated net actuarial gain	$	4.2		$	1.3		$	23.1		$	17.4		$	8.2		$	5.2
Prior service cost		(7.6	)		(6.1	)		—			—			(14.3	)		(16.0	)
Total	$	(3.4	)	$	(4.8	)	$	23.1		$	17.4		$	(6.1	)	$	(10.8	)

1.The prior service cost relating to our pension plans in 2024 resulted from an amendment to the Kaiser Aluminum Warrick pension plan clarifying certain plan provisions going back to the date of our acquisition of Warrick. The prior service cost relating to our pension plans in 2023 resulted from a new four-year collective bargaining agreement with the USW Local 104. In connection with the agreement, we amended the Kaiser Aluminum Warrick pension plan to increase certain pension benefits for covered plan participants. The prior service credit relating to the Salaried VEBA in 2023 resulted from a decrease in the annual healthcare reimbursement benefit for plan participants.

2.The actuarial gain relating to our pension plans in 2024 was comprised of a $2.2 million gain due to a change in the discount rate, partially offset by a $0.3 million loss due to changes in census information and a $0.3 million loss recognized in conjunction with a group annuity purchase. The actuarial loss relating to our pension plans in 2023 was comprised of a $0.5 million loss due to a change in the discount rate and a $0.3 million gain due to changes in census information. The actuarial gain relating to the OPEB in 2024 was comprised of a $6.5 million gain due to changes in census information, a $3.3 million gain due to a change in the discount rate, a $3.2 million gain due to a change in morbidity assumptions, a $3.3 million loss due to a change in the trend rate assumption, and a $2.9 million loss due to a change in the projected depletion year. The actuarial gain relating to the OPEB in 2023 was comprised of a $2.7 million gain due to a change in the projected depletion year, a $2.5 million gain due to changes in census information, a $3.1 million loss due to a change in the trend rate assumption, and a $1.4 million loss due to a change in the discount rate. The actuarial gain relating to the Salaried VEBA in 2024 was comprised of a $1.4 million gain due to a change in the discount rate, a $0.1 million gain due to changes in census information, and a $0.1 million loss due to a change in the trend rate assumption.

The actuarial loss relating to the Salaried VEBA in 2023 was comprised of a $0.7 million loss due to a change in the discount rate and a $0.3 million gain due to changes in census information.

3.In the fourth quarter of 2024, we entered into a group annuity purchase agreement under which approximately $4.5 million of obligations for certain participants of the Kaiser Aluminum Canada Limited Retirement Plan for Salaried Employees were transferred to an insurance company. The annuitization was funded through existing plan assets and does not change the amount of the monthly pension benefits received by the affected participants.

4.For the pension plans, the benefit obligation is the projected benefit obligation. For the Salaried VEBA and OPEB, the benefit obligation is the APBO.

5.At December 31, 2024, Net funded status relating to the pension plans consisted of $1.6 million within Other assets and $9.8 million within Pension and OPEB on our Consolidated Balance Sheets. At December 31, 2023, Net funded status relating to the pension plans consisted of $1.3 million within Other assets and $11.3 million within Pension and OPEB on our Consolidated Balance Sheets. Of the Net funded status relating to the OPEB at December 31, 2024, $3.1 million was included within Accrued salaries, wages and related expenses and $61.6 million was included within Pension and OPEB on our Consolidated Balance Sheets. Of the Net funded status relating to the OPEB at December 31, 2023, $3.3 million was included within Accrued salaries, wages and related expenses and $65.5 million was included within Pension and OPEB on our Consolidated Balance Sheets. Net funded status relating to the Salaried VEBA at December 31, 2024 and December 31, 2023 was included within Net liabilities of Salaried VEBA on our Consolidated Balance Sheets.

The accumulated benefit obligation for the pension plans was $29.8 million and $29.6 million at December 31, 2024 and December 31, 2023, respectively. We expect to contribute $4.5 million to the pension plans in 2025.

The following table presents the net benefits expected to be paid (in millions of dollars):

	Year Ended December 31,
	2025		2026		2027		2028		2029		2030-2034
Pension benefit payments	$	0.7	$	0.9	$	1.1	$	1.3	$	1.7	$	11.7
Salaried VEBA benefit payments1		5.3		5.1		4.9		4.6		4.3		16.9
OPEB payments		3.1		3.8		4.4		5.1		5.8		34.8
Total	$	9.1	$	9.8	$	10.4	$	11.0	$	11.8	$	63.4

1.Such amounts are based on benefit amounts and certain key assumptions obtained from the Salaried VEBA trustees and will be paid out of the Salaried VEBA plan assets. We have an ongoing obligation to make variable cash contributions to the Salaried VEBA, up to a maximum of $2.9 million annually based on our cash flow.

Plan Assets. The fundamental goal underlying our pension plan investment policy is to ensure that the assets of the plans are invested in a prudent manner to earn a rate of return over time to meet the obligations of the plans as these obligations come due. Risk management practices include diversification across asset classes and periodic rebalancing toward established asset allocation targets. Our investment policy permits variances from the targets within certain parameters.

The following table presents the weighted-average target and actual asset class allocations for our pension plans:

Asset class	2024 Target allocation	As of December 31, 2024
Equities	56%	55%
Fixed income	38%	38%
Real estate investments	5%	6%
Cash and short-term investments	1%	1%

Fair Value of Plan Assets. The plan assets of our pension plans and the Salaried VEBA are measured annually on December 31 and reflected in our Consolidated Balance Sheets at fair value. In determining the fair value of the plan assets at an annual period end, we utilize primarily the results of valuations supplied by the investment advisors responsible for managing the assets of each plan, which we independently review for reasonableness. With respect to the Salaried VEBA, the investment advisors providing the valuations are engaged by the Salaried VEBA trustees.

Certain plan assets are valued based upon unadjusted quoted market prices in active markets that are accessible at the measurement date for identical, unrestricted assets (e.g., liquid securities listed on an exchange). Such assets are classified within Level 1 of the fair value hierarchy.

The following table presents the fair value of plan assets at December 31, 2024 and 2023, classified under the appropriate level of the fair value hierarchy (in millions of dollars):

	December 31, 2024		December 31, 2023
Plan Assets in the Fair Value Hierarchy:	Level 1
Salaried VEBA – Equity investment funds in registered investment companies1	$	25.2	$	25.5
Salaried VEBA – Fixed income investment funds in registered investment companies2		16.8		16.5
Salaried VEBA – Cash and money market investments		0.2		—
Pension plans – Diversified investment funds in pooled separate accounts3		17.1		11.2
Pension plans – Diversified investment funds in registered investment companies4		5.4		9.3
Deferred compensation program – Diversified investment funds in registered investment companies4		11.9		11.1
Total plan assets in the fair value hierarchy	$	76.6	$	73.6

1.Equity investment funds in registered investment companies. This category represents investments in equity funds.

2.Fixed income investment funds in registered investment companies. This category represents investments in various fixed income funds with multiple registered investment companies. Such funds invest primarily in bonds, debentures, notes, securities with equity and fixed-income characteristics, cash equivalents, securities backed by mortgages and other assets, loans, pooled or collective investment vehicles made up of fixed‑income securities and other fixed-income obligations of banks, corporations, and governmental authorities.

3.Diversified investment funds in pooled separate accounts. The plan assets are invested in various pooled separate accounts that hold a diversified portfolio of: (i) equity and equity-related securities of U.S. and non-U.S. issuers across all market capitalizations; (ii) fixed income securities such as corporate bonds and government bonds; and (iii) commercial real estate, including mortgage loans which are backed by the associated properties. The pooled separate accounts are valued daily based on the market value of the underlying net assets in each separate account. The majority of the underlying net assets have observable Level 1 pricing inputs which are used to determine the unit value of the pooled separate account which is not publicly quoted.

4.Diversified investment funds in registered investment companies. The assets in the rabbi trust are invested in investment funds that hold a diversified portfolio of: (i) U.S. and international debt and equity securities; (ii) fixed income securities such as corporate bonds and government bonds; (iii) mortgage-related securities; and (iv) cash and cash equivalents.

The following table presents the total expense related to all benefit plans (in millions of dollars):

	Year Ended December 31,
	2024		2023		2022
Defined contribution plans1	$	18.6	$	18.1	$	17.1
Deferred compensation plan2		1.3		1.2		(0.6	)
Multiemployer pension plans1,3		6.1		5.6		5.2
Net periodic postretirement and postemployment benefit cost relating to defined benefit plans2,3,4		9.0		13.4		13.1
Total	$	35.0	$	38.3	$	34.8

1.Substantially all of these charges related to employee benefits are in COGS with the remaining balance in SG&A and R&D within our Statements of Consolidated Income (Loss).

2.Deferred compensation plan expense and the current service cost component of Net periodic postretirement and postemployment benefit cost relating to Salaried VEBA are included within our Statements of Consolidated Income (Loss) in SG&A and R&D for all periods presented. All other components of Net periodic postretirement and postemployment benefit cost relating to Salaried VEBA are included within Other income, net, in our Statements of Consolidated Income (Loss).

3.See Note 6 for more information on our multiemployer defined benefit pension plans. For the year ended December 31, 2024, the expense presented excludes a $4.6 million charge to Restructuring costs (see Note 12).

4.The current service cost component of Net periodic postretirement and postemployment benefit cost relating to both the pension plans and the OPEB plan is included within COGS in our Statements of Consolidated Income (Loss) for all periods presented. All other components of Net periodic postretirement and postemployment benefit cost relating to both the pension plans and the OPEB plan are included within Other income, net, in our Statements of Consolidated Income (Loss).

Components of Net Periodic Postretirement and Postemployment Benefit Cost. The following table presents the components of Net periodic postretirement and postemployment benefit cost relating to our defined benefit plans (in millions of dollars):

	Pension Plans									OPEB								Salaried VEBA
	Year Ended December 31,									Year Ended December 31,								Year Ended December 31,
	2024			2023			2022			2024			2023			2022		2024			2023			2022
Service cost	$	3.6		$	3.8		$	5.8		$	1.1		$	1.1		$	1.6	$	—			—		$	0.1
Interest cost		1.6			1.3			0.6			3.3			3.4			2.2		2.2			2.9			1.9
Expected return on plan assets		(1.4	)		(1.1	)		(0.9	)		—			—			—		(2.2	)		(2.2	)		(3.1	)
Amortization of prior service cost1		0.8			0.4			—			—			—			—		1.7			4.9			4.9
Amortization of net actuarial gain		—			—			—			(1.1	)		(1.1	)		—		(0.1	)		—			—
Settlement gain recognized		(0.5	)		—			—			—			—			—		—			—			—
Total net periodic postretirement and postemployment benefit cost	$	4.1		$	4.4		$	5.5		$	3.3		$	3.4		$	3.8	$	1.6		$	5.6		$	3.8

1.We amortize prior service cost on a straight-line basis over the average remaining years of service of the active plan participants.