In this Annual Report on Form 10-K (this “Report”), unless the context otherwise requires, references in these notes to consolidated financial statements to “Kaiser Aluminum Corporation,” “we,” “us,” “our,” “the Company” and “our Company” refer collectively to Kaiser Aluminum Corporation and its subsidiaries.

Organization and Nature of Operations. Kaiser Aluminum Corporation specializes in the production of semi-fabricated specialty aluminum mill products, such as aluminum plate and sheet and extruded and drawn products, for the following end market applications: (i) aerospace and high strength (“Aero/HS products”); (ii) automotive (“Automotive Extrusions”); (iii) general engineering (“GE products”); and (iv) and other industrial (“Other products”). Our business is organized into one operating segment. See Note 17 for additional information regarding our business, product and geographical area information and concentration of risk.

Principles of Consolidation and Basis of Presentation. Our consolidated financial statements include the accounts of our wholly owned subsidiaries and are prepared in accordance with United States generally accepted accounting principles (“GAAP”) and the rules and regulations of the Securities and Exchange Commission (“SEC”). Intercompany balances and transactions are eliminated.

Coronavirus Disease 2019 (“COVID-19”) Pandemic. Beginning in March 2020, the COVID-19 pandemic significantly impacted our industry, causing demand for our products, primarily in our aerospace and automotive end markets, to decline. We instituted operational measures in response to financial impacts caused by the reduced demand. In March 2020, we suspended repurchases of our common stock. During the quarter ended June 30, 2020, we: (i) began limiting capital spending to critical sustaining projects (see Note 2 for discussion of idled projects); (ii) early settled firm commitments with corresponding fair value hedges and reduced forecasts with respect to purchase transactions with corresponding cash flow hedges (see Note 8 ); (iii) settled all outstanding available for sale securities (see Note 8); (iv) issued $350.0 million of new unsecured senior notes (see Note 9); and (v) initiated a plan of restructuring (see Note 12).

Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in accordance with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities known to exist as of the date the financial statements are published and the reported amounts of revenues and expenses during the reporting period. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of our consolidated financial statements; accordingly, it is possible that the actual results could differ from these estimates and assumptions, which could have a material effect on the reported amounts of our consolidated financial position and results of operations. The severity, magnitude and duration, as well as the economic consequences of the COVID-19 pandemic, are uncertain, rapidly changing and difficult to predict. Therefore, our accounting estimates and assumptions may change over time in response to the COVID-19 pandemic and may change materially in future periods.

Fair Value Measurements. We apply the fair value hierarchy established by GAAP for the recognition and measurement of certain financial assets and liabilities. An asset or liability’s fair value classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. In determining fair value, we utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible and consider counterparty risk in our assessment of fair value.

We also review the underlying inputs that are significant to the fair value measurement of financial instruments to determine if a transfer among hierarchy levels is appropriate. We historically have not had significant transfers into or out of each hierarchy level.

Financial assets and liabilities that we measure at fair value each period include our derivative instruments, equity investments related to our deferred compensation plan and debt investment securities classified as available for sale securities (see Note 5 and Note 8). Additionally, we measure at fair value once each year at December 31 our Canadian defined benefit pension plan and the plan assets of the Salaried VEBA (defined in Note 5). 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. We record our remaining financial assets and liabilities at carrying value.

Goodwill is tested for impairment during the fourth quarter on an annual basis, as well as on an interim basis, as warranted, at the time of relevant events and changes in circumstances. Intangible assets with definite lives are initially recognized at fair value and subsequently amortized over the estimated useful lives to reflect the pattern in which the economic benefits of the intangible assets are consumed. In the event the pattern cannot be reliably determined, we use a straight-line amortization method. Whenever events or changes in circumstances indicate that the carrying amount of the intangible assets may not be recoverable, the intangible assets are reviewed for impairment. See Note 4 for a discussion of our business acquisition in 2018 and the goodwill impairment charges we recorded during 2019.

For a majority of our remaining non-financial assets and liabilities, which include inventories, debt issuance costs and property, plant and equipment, we are not required to measure their fair value on a recurring basis. However, if certain triggering events occur, an evaluation of the affected non-financial asset or liability will be required, which could result in a reduction to the carrying amount of such asset or liability. See “Property, Plant and Equipment, Net” below for a discussion of impairment charges on idled assets recorded during 2020, 2019 and 2018.

Cash and Cash Equivalents. We consider only those short-term, highly liquid investments which, when purchased, have maturities of 90 days or less to be cash equivalents. Our cash equivalents consist primarily of funds in commercial paper, money market funds and other highly liquid investments, which are classified within Level 1 of the fair value hierarchy with the exception of commercial paper, which is classified within Level 2 of the fair value hierarchy (see Note 8).

Restricted Cash. We are required to keep on deposit certain amounts that are pledged or held as collateral relating to workers’ compensation and other agreements. We account for such deposits as restricted cash (see Note 16). From time to time, such restricted funds could be returned to us or we could be required to pledge additional cash.

Available for Sale Securities. We account for investments in certain marketable debt securities as available for sale securities. Such securities are recorded at fair value (see Note 8), with net unrealized gains and losses, net of income taxes, reflected in Accumulated other comprehensive loss as a component of Stockholders’ equity. Realized gains and losses from the sale of marketable debt securities, if any, are determined on a specific identification basis. Debt investment securities with an original maturity of 90 days or less are classified as Cash and cash equivalents (see Note 2). Debt investment securities with an original maturity of greater than 90 days are presented as Short-term investments on our Consolidated Balance Sheets. In addition to debt investment securities, we also hold assets in various investment funds managed by a third-party trust in connection with our deferred compensation program (see Note 5).

Trade Receivables and Allowance for Credit Losses. Trade receivables primarily consist of amounts billed to customers for products sold. Accounts receivable are generally due within 30 to 90 days. For the majority of our receivables, we establish an allowance for credit losses based upon collection experience and other factors including, but not limited to, customer credit ratings, bankruptcy filings, published or estimated credit default rates, age of receivables, expected loss rates and collateral exposures. On certain other receivables where we are aware of a specific customer’s inability or reluctance to pay, an allowance for credit losses is established against amounts due, to reduce the net receivable balance to the amount we reasonably expect to collect. However, if circumstances change, our estimate of the recoverability of accounts receivable could be different. Circumstances that could affect our estimates include, but are not limited to, customer credit issues and general economic conditions. Accounts are written off once deemed to be uncollectible. Any subsequent cash collections relating to accounts that have been previously written off are typically recorded as a reduction to total bad debt expense in the period of payment. Write-offs for 2020, 2019 and 2018 were immaterial to our consolidated financial statements.

Inventories. Inventories are stated at the lower of cost or market value. Finished products, work-in-process and raw material inventories are stated on the last-in, first-out (“LIFO”) basis. At December 31, 2020 and December 31, 2019, the cost of our inventory on a first-in, first-out (“FIFO”) basis, which approximates the current replacement cost, exceeded its stated LIFO value by $8.4 million and $11.9 million, respectively. During the year ended December 31, 2020, we decremented a prior year, lower cost LIFO layer, which resulted in a benefit of $0.2 million. During the year ended December 31, 2019, we decremented a prior year, higher cost LIFO layer which resulted in a charge of $3.6 million. Other inventories are stated on the FIFO basis and consist of operating supplies, which are materials and supplies to be consumed during the production process. Inventory costs consist of material, labor and manufacturing overhead, including depreciation. Abnormal costs, such as idle facility expenses, freight, handling costs and spoilage, are accounted for as current period charges (see Note 2 for the components of inventories).

Replacement Parts. Replacement parts consist of preventative maintenance and capital spare parts, which are stated on the FIFO basis. Replacement parts are recorded within Prepaid expenses and other current assets or Other assets depending on whether or not the expected utilization of the replacement parts is to occur within the next 12 months.

Property, Plant and Equipment, Net. Property, plant and equipment, net, is recorded at cost and includes construction in progress (see Note 2). Interest related to the construction of qualifying assets is capitalized as part of the construction costs. The amount of interest expense capitalized as construction in progress was $1.0 million, $1.6 million and $1.7 million during 2020, 2019 and 2018, respectively.

Depreciation is computed using the straight-line method at rates based on the estimated useful lives of the various classes of assets. Finance lease assets and leasehold improvements are amortized on a straight-line basis over the shorter of the estimated useful lives of the assets or the lease term. The estimated useful lives are as follows:

		Range (in years)
Land improvements		3-25
Buildings and leasehold improvements		2-45
Machinery and equipment		1-22
Finance lease assets		1-10

Depreciation expense is not included in Cost of products sold, but is included in Depreciation and amortization.

Property, plant and equipment are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset or group of assets may not be recoverable. We regularly assess whether events and circumstances with the potential to trigger impairment have occurred and rely on a number of factors, including operating results, business plans, economic projections and anticipated future cash flow, to make such assessments. We use an estimate of the future undiscounted cash flows of the related asset or asset group over the estimated remaining life of such asset(s) in measuring whether the asset(s) are recoverable.

We recorded impairment charges of $0.5 million, $0.9 million and $1.4 million in 2020, 2019 and 2018, respectively, to reflect the scrap value of idled assets we determined not to deploy for future use. Asset impairment charges are included in Other operating (income) charges, net, in our Statements of Consolidated Income.

We classify assets as held for sale only when an asset is being actively marketed and expected to sell within 12 months. Assets held for sale are initially measured at the lesser of the assets’ carrying amount and the fair value less costs to sell.

Derivative Financial Instruments. Consistent with guidelines established by management and approved by our Board of Directors, we use derivative financial instruments to mitigate our exposure to changes in the market price of aluminum, certain alloying metals, energy and, to a lesser extent, foreign currency exchange rates. We do not use derivative financial instruments for trading or other speculative purposes. Hedging transactions are executed centrally on behalf of all of our operations to minimize transaction costs, monitor consolidated net exposures and allow for increased responsiveness to changes in market factors.

We reflect the fair value of all of our derivative instruments on our Consolidated Balance Sheets. The fair value of hedges settling within one year is included in Prepaid expenses and other current assets or Other accrued liabilities. The fair value of hedges settling beyond one year is included in Other assets or Long-term liabilities. Cash flows related to all of our derivative instruments are reported in our Statements of Consolidated Cash Flows within the same category as the items being hedged. See Note 8 for additional information on our derivative financial instruments.

Self Insurance of Workers’ Compensation and Employee Healthcare Liabilities. We self-insure the majority of the costs of workers’ compensation benefits and employee healthcare benefits and rely on insurance coverage to protect us from large losses on individual claims. Workers’ compensation liabilities are based on a combination of estimates for: (i) incurred-but-not-reported claims and (ii) the ultimate expense of incurred claims. Such estimates are based on judgment, using our historical claims data and information and analysis provided by actuarial and claims advisors, our insurance carriers and other professionals. As of December 31, 2020, we revised our methodology of calculating our estimated workers’ compensation liabilities from a discounted basis to an undiscounted basis, resulting in a charge of $0.6 million and an ending liability of $29.8 million as of December 31, 2020. Our estimate for unpaid claim liabilities, gross of insurance recoverables on an undiscounted basis was $29.2 million at December 31, 2019, of which we recorded $26.6 million using a discount rate of 1.75%. Accrued liabilities for employee healthcare benefits, which are estimates of unpaid incurred medical and prescription drug costs as provided by our healthcare administrators, were $3.1 million and $3.5 million at December 31, 2020 and December 31, 2019, respectively.

Debt Issuance Costs. Costs incurred in connection with debt financing are deferred and amortized over the estimated term of the related borrowing. Such amortization is included in Interest expense and may be capitalized as part of construction in progress (see Note 9).

Conditional Asset Retirement Obligations (“CAROs”). We have CAROs at several of our manufacturing facilities. Our CAROs can be separated into two primary categories: (i) legal obligations related to the removal and disposal of asbestos and (ii) asset retirement obligations related to future lease terminations. The majority of our CAROs relate to the first category and consist of incremental costs that would be associated with the removal and disposal of asbestos (all of which is believed to be fully contained

and encapsulated within walls, floors, roof, piping or equipment insulation) of certain of our older facilities if such facilities were to undergo major renovation or be demolished. We estimate incremental costs for special handling, removal and disposal costs of materials that may or will give rise to CAROs and then discount the expected costs back to the current year using a credit-adjusted, risk-free rate. When it is unclear when or if CAROs will be triggered, we use probability weighting for possible timing scenarios to determine the probability-weighted liability amounts that should be recognized in our consolidated financial statements (see Note 10).

Environmental Contingencies. With respect to environmental loss contingencies, we record a loss contingency whenever a contingency is probable and reasonably estimable (see Note 10). Accruals for estimated losses from environmental remediation obligations are generally recognized no later than the completion of the remedial feasibility study. Such accruals are adjusted as information develops or circumstances change. Costs of future expenditures for environmental remediation obligations are not discounted to their present value. Accruals for expected environmental costs are included in Other accrued liabilities or Long-term liabilities, as appropriate (see Note 2). Environmental expense relating to continuing operations is included in Cost of products sold excluding depreciation and amortization and other items (“Cost of products sold” or “COGS”) in our Statements of Consolidated Income. Environmental expense relating to non-operating locations is included in Selling, general, administrative, research and development (“SG&A and R&D”) in our Statements of Consolidated Income.

Revenue Recognition. We recognize revenue as we fulfill our performance obligations and transfer control of products to our customers. For products that have an alternative use and/or for which we do not have an enforceable right to payment (including a reasonable profit) during the production process, we recognize revenue at a point in time. For products that have no alternative use and for which we have an enforceable right to payment (including a reasonable profit) throughout the production process, we recognize revenue over time. In general, a majority of our Aero/HS products and our Automotive Extrusions are recognized over time, with the remainder of our products recognized at a point in time.

For the majority of our business, contracts with customers begin when we acknowledge a purchase order for a specific customer order of product to be delivered in the near term. These purchase orders are short term in nature, although they may reference a longer term “blanket purchase order” or a “terms and conditions” agreement, both of which may span multiple years. For revenue recognized at a point in time, transfer of control usually occurs upon shipment or upon customer receipt of the product, depending on shipping terms. For contracts recognized over time, control transfer occurs incrementally during our production process as progress is made on fulfilling the performance obligation. We use the input method of determining our progress, capturing direct costs beginning at the point that billet or cast ingot is introduced into production at either the extrusion phase or the rolling phase, respectively. We believe the input method more accurately reflects the transfer of control as it represents the best information available of work completed to date for which we have an enforceable right to payment. For products in production, we recognize revenue using estimates of the cost incurred to date plus a reasonable margin. As the duration of our contracts for accounting purposes is typically less than one year, we do not present quantitative information about the aggregate transaction price allocated to unsatisfied performance obligations at the end of the reporting period.

We adjust the amount of revenue recognized on all products, regardless of timing of revenue recognition, for variable price consideration, which could include metal market price adjustments, volume rebates and sales discounts. We estimate rebate and discount values based on forecasted order data and historical payment trends for specific customers, adjusted as necessary at each reporting period. Accounts receivable is recorded when our right to consideration becomes unconditional. Payment terms for a majority of our domestic customers are 30 days after invoice date. To accommodate shipping time to overseas locations, payment terms for foreign customers are typically several weeks longer than domestic terms. As such, we do not adjust the promised amount of consideration for the effects of a significant financing component as we do not expect the period between the transfer of control of products to our customers and receipt of payment will be greater than one year.

Contract assets primarily relate to our enforceable right to consideration for work completed but not billed at the reporting date on contracts for products recognized over time. Contract assets also include amounts related to our contractual right to consideration for finished goods recognized over time that were in transit as of period end.

Incremental Costs of Obtaining a Contract. We expense the costs of obtaining a contract as incurred as the amortization period of the asset that we otherwise would have recognized is one year or less.

Shipping and Handling Activities. We account for shipping and handling activities that occur after the customer has obtained control of a product as fulfillment activities (i.e., an expense) rather than as a promised service (i.e., a revenue element).

Advertising Costs. Advertising costs, which are included in SG&A and R&D, are expensed as incurred. Advertising costs for 2020, 2019 and 2018 were $0.2 million, $0.4 million and $0.3 million, respectively.

Research and Development Costs. Research and development costs, which are included in SG&A and R&D, are expensed as incurred. Research and development costs for 2020, 2019 and 2018 were $9.1 million, $10.5 million and $9.8 million, respectively.

Major Maintenance Activities. All major maintenance costs are accounted for using the direct expensing method.

Stock-Based Compensation. Stock-based compensation in the form of service-based awards is provided to executive officers, certain employees and non-employee directors and is accounted for at fair value. We measure the cost of services received in exchange for an award of equity instruments based on the grant-date fair value of the award and the number of awards expected to ultimately vest. The grant-date fair value is determined based on the stock price on the date of grant, adjusted for expected dividends or dividend equivalents to be paid during the vesting period.

We also grant performance-based awards to executive officers and other key employees. The methodology used to value these performance-based awards is based on the nature of the performance conditions within those awards. Awards that are subject to performance conditions pertaining to total shareholder return (market-based awards) are valued on the date of grant using a Monte Carlo valuation model. The key assumptions in applying this model are an expected volatility and a risk-free interest rate. Awards with certain other performance conditions (non-market-based awards) are valued based on our stock price at the date of grant. Our non‑market-based awards have performance conditions pertaining to our cost performance, economic value added performance and adjusted EBITDA margin performance, which is measured by our adjusted earnings before interest, taxes, depreciation and amortization (“Adjusted EBITDA”) as a percentage of value added revenue. Holders of performance-based awards receive a one-time payment at the time of issuance of vested shares based on the total dividends they would have received if the vested shares had been held of record from the date of grant through the date of issuance. For more information on our stock-based compensation (see Note 7).

The cost of service-based awards, including time-vested restricted stock and performance shares, is recognized as an expense over the requisite service period of the award on a straight-line basis. Adjustments to expense related to forfeitures are recorded in the period in which they occur. For performance shares with performance conditions pertaining to our cost performance, economic value added performance and Adjusted EBITDA margin performance, the related expense is updated quarterly by adjusting the estimated number of shares expected to vest based on the most probable outcome of the performance condition (see Note 7).

ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), was issued in June 2016. Under ASU 2016-13, existing guidance on reporting credit losses for trade and other receivables and available for sale debt securities have been replaced with a new forward-looking “expected loss” model that has resulted in the earlier recognition of allowances for losses. Our adoption of ASU 2016-13 during the quarter ended March 31, 2020 using the modified retrospective transition approach did not result in a material impact on our consolidated financial statements.

ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”), was issued in August 2018. Under ASU 2018-15, requirements for capitalizing implementation costs incurred in a hosting arrangement (cloud computing) that is a service contract are to be aligned with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. We adopted ASU 2018-15 during the quarter ended March 31, 2020 using the prospective transition approach. The implementation costs we capitalized during the twelve months ended December 31, 2020 were included in both Prepaid expenses and other current assets and Other assets in our Consolidated Balance Sheets. The corresponding cash flows related to these arrangements were included in Net cash provided by operating activities in our Statements of Consolidated Cash Flows.

ASU No. 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”), was issued in December 2019. Under ASU 2019-12, the accounting for income taxes is simplified by eliminating certain exceptions and implementing additional requirements which result in a more consistent application of ASC 740 Income Taxes. Most amendments within ASU 2019-12 are required to be applied on a prospective basis, while certain amendments must be applied on a retrospective or modified retrospective basis. We are currently in the process of evaluating the impact of adopting ASU 2019-12 in 2021, but do not expect it to have a material impact on our consolidated financial statements.