What changed in this filing

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Item 8. Financial Statements and Supplementary Data

2024-03-15 compared with 2023-02-27 · 377 added, 359 removed, 1234 unchanged (37% of the section changed)

5 unchanged sentences

Consolidated Balance Sheets at December 31, 2023 and 2022 53

Consolidated Statements of Shareholders’ Equity for the Years Ended December 31, 2022, 2021 and 2020 48

Consolidated Statements of Cash Flows for the Years Ended December 31, 2023, 2022 and 2021 54

Consolidated Statements of Shareholders’ Equity for the Years Ended December 31, 2023, 2022 and 2021 56

Notes to the Consolidated Financial Statements 57

4 unchanged sentences

In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2023 and 2022, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2023, in conformity with accounting principles generally accepted in the United States of America.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2022, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated February 27, 2023, expressed an unqualified opinion on the Company's internal control over financial reporting.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated March 15, 2024, expressed an adverse opinion on the Company's internal control over financial reporting because of a material weakness.

Basis for Opinion

9 unchanged sentences

We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments.

The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Critical Audit Matters

The critical audit matters communicated below are matters arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments.

The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing a separate opinion on the critical audit matters or on the accounts or disclosures to which it relates.

Impairment of Long-Lived Assets — Refer to Note 1 to the financial statements.

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◦ Inspecting minutes of the board of directors and committees of executive management to understand if there were factors that would represent potential impairment indicators for the Company’s asset groups.

Acquisition of Jamalco— Refer to Note 2 to the financial statements

Critical Audit Matter Description

As discussed in Note 2 to the consolidated financial statements, the Company 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.

The remaining 45% interest in Jamalco is owned by Clarendon Alumina Production Limited ("CAP"), which in turn is owned by the Government of Jamaica.

The acquisition is expected to result in a bargain purchase gain in part due to the seller experiencing financial distress following curtailment of Jamalco's operations in the second half of 2021 due to a facility fire, with operations restarting in the second half of 2022.

We identified the accounting for the acquisition as a critical audit matter because determining the fair value of identified assets acquired, liabilities assumed and noncontrolling interest requires judgment and involves the use of significant estimates and assumptions.

This required a high degree of auditor judgment and an increased extent of effort, including the need to involve our fair value specialists, when performing audit procedures to evaluate whether management appropriately accounted for the business combination.

How the Critical Audit Matter Was Addressed in the Audit

Our procedures related to auditing the fair value of identified assets acquired, liabilities assumed and noncontrolling interest included the following, among others:

• Testing the effectiveness of controls over the purchase price accounting, including management’s review of the valuation performed by their specialists.

• Testing the account balances as of opening balance sheet date and the purchase price accounting adjustments.

• Evaluating the reasonableness of the valuation methodology used by the Company to value the business enterprise value, personal property, real property, mineral reserves and asset retirement obligations with the assistance of our fair value specialists.

• Evaluating the accounting treatment for the deferred bargain purchase gain and non-controlling interest associated with the acquisition.

• Evaluating the Company's disclosures related to the acquisition to assess their conformity with the applicable accounting standards.

/s/ Deloitte & Touche LLP

Chicago, Illinois

February 27, 2023

March 15, 2024

We have served as the Company's auditor since 1992.

3 unchanged sentences

We have audited the internal control over financial reporting of Century Aluminum Company and subsidiaries (the “Company”) as of December 31, 2023, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2022, based on criteria established in Internal Control — Integrated Framework (2013) issued by COSO.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated financial statements as of and for the year ended December 31, 2022, of the Company and our report dated February 27, 2023, expressed an unqualified opinion on those financial statements.

In our opinion, based on the material weakness identified below on the achievement of the objectives of the control criteria, the Company has not maintained effective internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control — Integrated Framework (2013) issued by COSO.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated financial statements as of and for the year ended December 31, 2023, of the Company and our report dated March 15, 2024, expressed an unqualified opinion on those financial statements.

As described in the management report on Internal Control over Financial Reporting, management excluded from its assessment the internal control over financial reporting at Jamalco JV, which was acquired on May 2, 2023, and whose financial statements constitute 24.1% of total assets, and 6.9% of net sales of the consolidated financial statement amounts as of and for the year ended December 31, 2023.

Accordingly, our audit did not include the internal control over financial reporting at Jamalco JV.

Basis for Opinion

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A company’s internal control over financial reporting is a process 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.

A company’s internal control over financial reporting includes those policies and procedures that:

(1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company;

A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company;

(2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company;

(3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements.

Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Material Weakness

A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting, such that there is a reasonable possibility that a material misstatement of the company’s annual or interim financial statements will not be prevented or detected on a timely basis.

The following material weakness has been identified and included in management's assessment:

Management identified a deficiency in the design of internal control over financial reporting related to the application of purchase accounting to the 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.

This material weakness was considered in determining the nature, timing, and extent of audit tests applied in our audit of the consolidated financial statements as of and for the year ended December 31, 2023, of the Company, and this report does not affect our report on such financial statements.

/s/ Deloitte & Touche LLP

Chicago, Illinois

February 27, 2023

March 15, 2024

CENTURY ALUMINUM COMPANY

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Cost of goods sold 2,093.5 2,730.6 2,088.3

Gross profit (loss) 46.7 124.2 ( 36.5 )

Gross profit 91.9 46.7 124.2

Selling, general and administrative expenses 44.3 37.5 57.6

2 unchanged sentences

Operating income (loss) 31.8 ( 150.2 ) 66.0

Interest expense – Hawesville term loan — ( 1.6 ) ( 1.9 )

Interest expense - affiliates ( 1.8 ) — ( 1.6 )

Interest expense ( 33.7 ) ( 29.3 ) ( 28.8 )

Interest income 2.0 0.5 0.8

Net gain (loss) on forward and derivative contracts 197.1 ( 212.4 ) ( 17.3 )

Net (loss) gain on forward and derivative contracts ( 61.8 ) 197.1 ( 212.4 )

Loss on early extinguishment of debt — — ( 24.7 )

Other income - net 15.3 3.1 3.5

Income (loss) before income taxes and equity in earnings of joint ventures 33.4 ( 197.6 ) ( 126.3 )

Income tax (expense) benefit ( 47.4 ) 30.6 3.1

Other (loss) income - net ( 3.3 ) 15.3 3.1

(Loss) income before income taxes ( 66.8 ) 33.4 ( 197.6 )

Income tax benefit (expense) 14.6 ( 47.4 ) 30.6

Loss before equity in earnings of joint ventures ( 52.2 ) ( 14.0 ) ( 167.0 )

1 unchanged sentence

Net loss ( 52.3 ) ( 14.1 ) ( 167.1 )

LOSS PER COMMON SHARE:

Net loss attributable to noncontrolling interests ( 9.2 ) — —

Net loss attributable to Century stockholders $ ( 43.1 ) $ ( 14.1 ) $ ( 167.1 )

LOSS ATTRIBUTABLE TO CENTURY STOCKHOLDERS PER COMMON SHARE:

Basic and diluted $ ( 0.47 ) $ ( 0.15 ) $ ( 1.85 )

7 unchanged sentences

2023 2022 2021

Comprehensive loss:

Net loss $ ( 52.3 ) $ ( 14.1 ) $ ( 167.1 )

2 unchanged sentences

Defined benefit plans and other postretirement benefits:

Net (loss) gain arising during the period ( 5.9 ) 31.6 ( 13.4 )

OPEB curtailment gain ( 8.9 ) — —

Amortization of prior service benefit during the period ( 1.2 ) ( 3.1 ) ( 3.0 )

Net (gain) loss arising during the period ( 10.1 ) ( 5.9 ) 31.6

OPEB curtailment gain, net — ( 8.9 ) —

Amortization of prior service benefit (cost) during the period 0.1 ( 1.2 ) ( 3.1 )

Amortization of net loss during the period 6.2 4.8 8.4

2 unchanged sentences

Other comprehensive (loss) income ( 3.9 ) ( 11.7 ) 36.5

Total comprehensive loss $ ( 25.8 ) $ ( 130.6 ) $ ( 132.2 )

Comprehensive loss ( 56.2 ) ( 25.8 ) ( 130.6 )

Comprehensive loss attributable to noncontrolling interests ( 9.2 ) — —

Comprehensive loss attributable to Century stockholders $ ( 47.0 ) $ ( 25.8 ) $ ( 130.6 )

See notes to consolidated financial statements.

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Accounts receivable - net 53.7 66.9

Non-trade receivables 36.2 —

Due from affiliates 20.2 4.8

Manufacturing credit receivable 59.3 —

Inventories 477.0 398.8

7 unchanged sentences

Accounts payable, trade $ 249.5 $ 167.3

Accrued compensation and benefits 38.1 33.0

Due to affiliates 101.4 17.0

1 unchanged sentence

Derivative liabilities 1.4 9.7

Accrued employee benefits costs 9.9 8.9

Iceland term facility 13.3 —

revolving credit facility 90.0 63.6

Iceland revolving credit facility 35.0 50.0

Industrial revenue bonds 7.8 7.8

Deferred credit - preliminary bargain purchase gain 273.4 —

Current debt due to affiliates 10.0 —

Current maturities of long-term debt 38.3 146.1

Total current liabilities 763.0 410.7

Senior notes payable 246.6 245.8

Convertible senior notes payable 84.4 84.0

Grundartangi casthouse debt facility 49.4 —

Iceland term facility, net of current portion 1.2 —

Accrued pension benefits costs - less current portion 44.5 28.6

Accrued postretirement benefits costs - less current portion 67.6 93.3

Long-term debt 430.9 381.6

Accrued benefits costs - less current portion 120.3 118.0

Other liabilities 66.3 31.4

Leases - right of use liabilities 20.9 22.9

Due to affiliates - less current portion — 8.3

Deferred taxes 72.4 103.1

Asset retirement obligations - less current portion 49.5 19.6

Total noncurrent liabilities 739.4 662.0

7 unchanged sentences

Accumulated deficit ( 2,004.1 ) ( 1,961.0 )

Total shareholders’ equity 399.3 421.0

Total Century shareholders’ equity 355.6 399.3

Noncontrolling interest ( 11.5 ) —

Total equity 344.1 399.3

TOTAL $ 1,846.5 $ 1,472.0

1 unchanged sentence

CENTURY ALUMINUM COMPANY

CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY

(in millions)

Preferred stock Common stock Additional paid-in capital Treasury stock, at cost Accumulated other comprehensive loss Accumulated

deficit Total shareholders’ equity

Balance, December 31, 2019 $ 0.0 $ 1.0 $ 2,526.5 $ ( 86.3 ) $ ( 109.8 ) $ ( 1,656.4 ) $ 675.0

Net loss — — — — — ( 123.3 ) ( 123.3 )

Other comprehensive income (loss) — — — — ( 8.9 ) — ( 8.9 )

Share-based compensation — 0.0 3.5 — — — 3.5

Conversion of preferred stock to common stock 0.0 0.0 0.0 — — — 0.0

Balance, December 31, 2020 $ 0.0 $ 1.0 $ 2,530.0 $ ( 86.3 ) $ ( 118.8 ) $ ( 1,779.8 ) $ 546.1

Net loss — — — — — ( 167.1 ) ( 167.1 )

Other comprehensive income (loss) — — — — 36.5 — 36.5

Share-based compensation — 0.0 10.1 — — — 10.1

Conversion of preferred stock to common stock 0.0 0.0 0.0 — — — 0.0

Capped call premiums — — ( 4.6 ) — — — ( 4.6 )

Balance, December 31, 2021 $ 0.0 $ 1.0 $ 2,535.5 $ ( 86.3 ) $ ( 82.3 ) $ ( 1,946.9 ) $ 421.0

Net loss — — — — — ( 14.1 ) ( 14.1 )

Other comprehensive income (loss) — — — — ( 11.7 ) — ( 11.7 )

Share-based compensation — 0.0 4.1 — — — 4.1

Conversion of preferred stock to common stock 0.0 0.0 0.0 — — — 0.0

Balance, December 31, 2022 $ 0.0 $ 1.0 $ 2,539.6 $ ( 86.3 ) $ ( 94.0 ) $ ( 1,961.0 ) $ 399.3

See notes to consolidated financial statements.

CENTURY ALUMINUM COMPANY

CONSOLIDATED STATEMENTS OF CASH FLOWS

6 unchanged sentences

Lower of cost or NRV inventory adjustment — 39.6 —

(Gain) loss on derivative instruments ( 201.5 ) 102.9 15.7

Depreciation and amortization 73.4 82.6 83.0

Change in deferred tax provision (benefit) 44.2 ( 30.6 ) —

Unrealized loss (gain) on derivative instruments 87.1 ( 201.5 ) 102.9

Depreciation, depletion and amortization 74.7 73.4 82.6

Change in deferred tax (benefit) provision ( 30.8 ) 44.2 ( 30.6 )

Asset impairment — 159.4 —

OPEB curtailment gain ( 8.9 ) — —

Other postretirement benefits gain, net — ( 8.9 ) —

Loss on early extinguishment of debt — — 24.7

Other non-cash items - net 3.4 ( 22.8 ) ( 1.7 )

Change in operating assets and liabilities:

Change in operating assets and liabilities, net of acquisition:

Accounts receivable - net 36.9 13.7 ( 16.2 )

Non-trade receivables 4.1 — —

Manufacturing credit receivable ( 59.3 ) — —

Due from affiliates ( 15.5 ) 3.6 0.7

5 unchanged sentences

Ravenswood retiree legal settlement ( 2.0 ) ( 2.0 ) ( 2.0 )

Ravenswood PBGC settlement ( 2.4 ) — —

PBGC settlement ( 4.5 ) ( 2.4 ) —

Other - net 2.8 1.4 1.8

3 unchanged sentences

Proceeds from sale of property, plant and equipment 25.7 0.8 0.4

Acquisition of subsidiary net of cash acquired 11.5 — —

Net cash used in investing activities ( 57.8 ) ( 85.5 ) ( 82.6 )

1 unchanged sentence

Repayment of Senior Notes due 2025 — — ( 250.0 )

Proceeds from issuance of Senior Notes due 2025 — — 243.8

Repayment of Senior Notes due 2025 — ( 250.0 ) —

Early redemption and tender premiums paid — — ( 18.1 )

2 unchanged sentences

Repayments under Hawesville Term Loan — — ( 20.0 )

Borrowings under Vlissingen facility agreement 10.0 — —

Borrowings under revolving credit facilities 656.9 1,126.2 978.8

1 unchanged sentence

Debt issuance cost — ( 1.5 ) ( 7.4 )

Debt retirement cost — — ( 0.2 )

Purchase of capped calls related to Convertible Senior Notes — — ( 5.7 )

CENTURY ALUMINUM COMPANY

CONSOLIDATED STATEMENTS OF CASH FLOWS

(in millions)

Year Ended December 31,

2023 2022 2021

Borrowings under Grundartangi casthouse debt facility 55.0 50.0 —

Borrowings under Iceland term facility — 14.5 —

Net cash provided by financing activities 74.4 103.7 13.5

Repayments under Iceland term facility ( 13.5 ) — —

Carbon credit proceeds 36.8 — —

Net cash (used in) provided by financing activities ( 13.0 ) 74.4 103.7

CHANGE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH 34.8 14.8 ( 43.6 )

10 unchanged sentences

CENTURY ALUMINUM COMPANY

CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY

(in millions)

Preferred stock Common stock Additional paid-in capital Treasury stock, at cost Accumulated other comprehensive loss Accumulated

deficit Total Century equity Noncontrolling interest Total equity

Shares Amount Shares Amount

Balance, December 31, 2020 63,589 — 90,055,797 $ 1.0 $ 2,530.0 $ ( 86.3 ) $ ( 118.8 ) $ ( 1,779.8 ) $ 546.1 $ — $ 546.1

Net loss — — — — — — — ( 167.1 ) ( 167.1 ) — ( 167.1 )

Other comprehensive income (loss) — — — — — — 36.5 — 36.5 — 36.5

Share-based compensation — — 671,218 — 10.1 — — — 10.1 — 10.1

Conversion of preferred stock to common stock ( 5,047 ) — 504,596 — — — — — — — —

Capped call premiums — — — — ( 4.6 ) — — — ( 4.6 ) — ( 4.6 )

Balance, December 31, 2021 58,542 — 91,231,611 $ 1.0 $ 2,535.5 $ ( 86.3 ) $ ( 82.3 ) $ ( 1,946.9 ) $ 421.0 $ — $ 421.0

Net loss — — — — — — — ( 14.1 ) ( 14.1 ) — ( 14.1 )

Other comprehensive income (loss) — — — — — — ( 11.7 ) — ( 11.7 ) — ( 11.7 )

Share-based compensation — — 623,582 — 4.1 — — — 4.1 — 4.1

Conversion of preferred stock to common stock ( 4,688 ) — 468,785 — — — — — — — —

Balance, December 31, 2022 53,854 — 92,323,978 $ 1.0 $ 2,539.6 $ ( 86.3 ) $ ( 94.0 ) $ ( 1,961.0 ) $ 399.3 $ — $ 399.3

Net loss — — — — — — — ( 43.1 ) ( 43.1 ) ( 9.2 ) ( 52.3 )

Other comprehensive income (loss) — — — — — — ( 3.9 ) — ( 3.9 ) — ( 3.9 )

Share-based compensation — — 208,867 — 3.3 — — — 3.3 — 3.3

Conversion of preferred stock to common stock ( 1,570 ) — 157,019 — — — — — — — —

Noncontrolling interest of business acquired — — — — — — — — — ( 2.3 ) ( 2.3 )

Balance, December 31, 2023 52,284 $ — 92,689,864 $ 1.0 $ 2,542.9 $ ( 86.3 ) $ ( 97.9 ) $ ( 2,004.1 ) $ 355.6 $ ( 11.5 ) $ 344.1

See notes to consolidated financial statements.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

7 unchanged sentences

CASC operates a primary aluminum reduction facility in Goose Creek, South Carolina ("Mt.

In addition to our primary aluminum assets, our subsidiary, Century Aluminum Vlissingen B.V., owns and operates a carbon anode production facility located in Vlissingen, the Netherlands ("Vlissingen").

In addition to our primary aluminum assets, we have a 55 % joint venture interest in the Jamalco bauxite mining operation and alumina refinery in Jamaica ("Jamalco").

The Jamalco refinery supplies a substantial amount of the alumina used for production of primary aluminum at our aluminum smelter in Grundartangi, Iceland.

Additionally, our subsidiary, Century Aluminum Vlissingen B.V., owns and operates a carbon anode production facility located in Vlissingen, the Netherlands ("Vlissingen").

Carbon anodes are used in the production of primary aluminum and Vlissingen currently supplies carbon anodes to Grundartangi.

8 unchanged sentences

Actual results could differ from those estimates.

Certain prior period amounts included in current liabilities and non-current liabilities within the Consolidated Balance Sheets have been reclassified to conform with the current period presentation.

These reclassifications had no impact on the Company's net loss, earnings per share, balance sheet or cash flows.

Our consolidated financial statements include the consolidated results of the Jamalco joint venture, an unincorporated joint venture between the Company and Clarendon Alumina Production Limited.

Clarendon Alumina Production's interest in the joint venture is reflected as noncontrolling interest on the accompanying Consolidated Balance Sheet.

Revenue recognition — See Note 5.

1 unchanged sentence

The carrying amount of cash equivalents approximates fair value.

Accounts Receivable and Due from Affiliates — These amounts are net of an allowance for expected losses of $ 0.5 million and $ 1.0 million at December 31, 2022 and 2021, respectively.

Accounts Receivable and Due from Affiliates — These amounts are net of an allowance for expected losses of $ 0.5 million at both December 31, 2023 and 2022.

Inventories — Our inventories are stated at the lower of cost or net realizable value, using the first-in, first-out ("FIFO") and the weighted average cost method.

1 unchanged sentence

Reductions in net realizable value below cost basis at the end of a period will have an impact on our cost of goods sold as this inventory is sold in subsequent periods.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Property, Plant and Equipment — Property, plant and equipment is stated at cost.

Additions and improvements are capitalized when each asset is placed into service.

Asset and accumulated depreciation accounts are relieved for dispositions with resulting gains or losses included in Other income - net.

Asset and accumulated depreciation accounts are relieved for dispositions with resulting gains or losses included in Other (loss) income - net.

Maintenance and repairs are expensed as incurred.

3 unchanged sentences

Technology and software 3 to 7 years

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

During the second half of 2022, we fully curtailed production at our Hawesville facility and ceased our efforts to rebuild the fifth potline.

During 2022, we continued efforts to restart the curtailed capacity at our Mt.

Holly facility.

Restart work at the Mt.

Holly smelter was completed in the second quarter of 2022 bringing its operations to 75 % of Mt.

Holly's maximum production capacity.

All associated costs that meet the capitalization criteria have been capitalized as a component of property, plant and equipment.

The Company incurs deferred costs during the development stage of a mine life cycle.

Such costs include the construction of access and haul roads, detailed drilling and geological analysis to further define the grade and quality of the known bauxite, and overburden removal costs.

These costs relate to sections of the related mines where the Company is currently extracting bauxite or preparing for production in the near term.

These sections are outlined and planned incrementally and generally are mined over periods outlined in the Company's mine plans.

The amount of geological drilling and testing necessary to determine the economic viability of the bauxite deposit being mined is such that the reserves are considered to be proven.

Mineral reserves are amortized on a units-of-production basis.

Impairment of long-lived assets — The Company reviews property, plant and equipment ("long-lived assets") for impairment whenever events or changes in circumstances, known as triggering events, indicate that the carrying amount of a long-lived asset or an asset group may not be recoverable.

17 unchanged sentences

We contribute to our defined benefit pension plans based upon actuarial and economic assumptions designed to achieve adequate funding of the projected benefit obligations and to meet the minimum funding requirements.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Postemployment Benefits — We provide certain postemployment benefits to certain former and inactive employees and their dependents during the period following employment, but before retirement.

4 unchanged sentences

Derivative instruments may consist of variable to fixed financial contracts and back-to-back fixed to floating arrangements for a portion of our sale of primary aluminum, where we receive fixed and pay floating prices from our customers and to counterparties, respectively.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

From time to time, we may manage our exposure to fluctuations in the market price of power through financial instruments designed to protect our downside risk exposure.

7 unchanged sentences

dollar as compared to the Euro and the Icelandic krona ("ISK"), and the Chinese renminbi.

Grundartangi and Vlissingen use the U.S.

dollar as their functional currency, as contracts for sales of aluminum and purchases of alumina and power are denominated in U.S.

Transactions denominated in currencies other than the functional currency are recorded based on exchange rates at the time such transactions arise and any transaction gains and losses are reflected in Other income - net in the consolidated statements of operations.

Grundartangi, Vlissingen and Jamalco use the U.S.

dollar as their functional currency, as contracts for sales of aluminum and alumina and purchases of alumina and power are denominated in U.S.

Transactions denominated in currencies other than the functional currency are recorded based on exchange rates at the time such transactions arise and any transaction gains and losses are reflected in Other (loss) income - net in the consolidated statements of operations.

Financial Instruments — Receivables, certain life insurance policies, payables, borrowings under revolving credit facilities and debt related to industrial revenue bonds ("IRBs") are carried at amounts that approximate fair value.

7 unchanged sentences

In periods where we report net losses, we do not allocate these losses to the Convertible Preferred Stock for the computation of basic or diluted EPS.

Asset Retirement Obligations — We are subject to environmental regulations which create certain legal obligations related to the normal operations of our domestic primary aluminum smelter operations.

Our asset retirement obligations ("AROs") consist primarily of costs associated with the disposal of spent potliner used in the reduction cells of our domestic facilities.

AROs are recorded on a discounted basis at the time the obligation is incurred (when the potliner is put in service) and accreted over time for the change in the present value of the liability.

We capitalize the asset retirement costs by increasing the carrying amount of the related long-lived assets and depreciating these assets over their remaining useful lives.

Certain conditional asset retirement obligations ("CAROs") relate to the remediation of our primary aluminum facilities for hazardous material, such as landfill materials and asbestos which have not been recorded because they have an indeterminate settlement date.

CAROs are a legal obligation to perform an asset retirement activity in which the timing and/or method of settlement are conditional on a future event that may or may not be within our control.

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

Asset Retirement Obligations — We are subject to environmental regulations which create certain legal obligations related to the normal operations of our bauxite mine and alumina refinery and our domestic primary aluminum smelter operations.

Our asset retirement obligations ("AROs") consist primarily of costs associated with mine reclamation obligations, closure of bauxite residue areas, landfill closure, and the disposal of spent potliner used in the reduction cells of our domestic smelters.

AROs are recorded on a discounted basis at the time the obligation is incurred (when the potliner is put in service or upon disturbance of lands to be mined) and accreted over time for the change in the present value of the liability.

We capitalize the asset retirement costs by increasing the carrying amount of the related long-lived assets and depreciating these assets over their remaining useful lives.

Certain conditional asset retirement obligations ("CAROs") related to the remediation of our primary aluminum facilities for hazardous material, such as landfill materials and asbestos, have not been recorded because they have an indeterminate settlement date.

CAROs are a legal obligation to perform an asset retirement activity in which the timing and/or method of settlement are conditional on a future event that may or may not be within our control.

Concentrations of Credit Risk — Financial instruments, which potentially expose us to concentrations of credit risk, consist principally of trade receivables.

8 unchanged sentences

We have not issued any stock options since 2009.

Recently Adopted Accounting Standards

In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848),” as amended by ASU 2021-01 in January 2021, directly addressing the effects of reference rate reform on financial reporting as a result of the cessation of the publication of London Interbank Offered Rate ("LIBOR") and provides optional expedients for a limited period of time for accounting for contracts, hedging relationships, and other transactions affected by LIBOR or other reference rates expected to be discontinued.

These optional expedients can be applied from March 2020 through December 31, 2022.

In December 2022, the FASB issued ASU No.

2022-06, "Reference Rate Reform:

Deferral of the Sunset Date of Topic 848," which deferred the sunset date of Topic 848 from December 31, 2022 to December 31, 2024.

Arrangements that were entered into during the year ended December 31, 2022, including amendments to our U.S.

and Iceland revolving credit facilities and our new Iceland Term Facility no longer use LIBOR as a reference rate.

LIBOR continues to be the reference rate for our Grundartangi casthouse facility set to mature in 2028.

The phase out of LIBOR reference rates will occur at different dates and began on January 1, 2022.

Our adoption of this new standard occurred during the year ended December 31, 2022, in conjunction with the first phase-out of the LIBOR reference rate.

There was no material impact to our consolidated financial statements, nor do we expect the adoption of this standard to have a material impact on our consolidated financial statements during the LIBOR transition.

Acquisition of Jamalco

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.

The remaining 45 % interest in Jamalco is owned by Clarendon Alumina Production Limited ("CAP"), which in turn is owned by the Government of Jamaica.

The purchase price for the acquisition was $ 1.00 .

The acquisition was accounted for as a business combination under the acquisition method of accounting.

Determining the fair value of identified assets acquired, liabilities assumed and noncontrolling interest requires judgment and involves the use of significant estimates and assumptions.

The Company based its fair value estimates on assumptions it believes to be reasonable but are inherently uncertain.

These estimates and valuation of the property, plant and equipment, other assets, accrued and other current liabilities and long term liabilities as well as the related deferred bargain purchase gain and noncontrolling interest are preliminary as of December 31, 2023 and are subject to change as we finalize the valuation or if additional information about the facts and circumstances that existed at the acquisition date become available.

We expect to finalize the purchase price allocation as soon as practicable within the measurement period, but not later than one year following the acquisition date.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

The following table summarizes the estimated fair value of identified assets acquired, liabilities assumed and noncontrolling interest at the date of acquisition:

Preliminary purchase price allocation Amount

Identifiable assets acquired and liabilities assumed

Cash and cash equivalents $ 19.4

Restricted cash 8.3

Accounts receivable - net 7.7

Non-trade receivables 40.4

Inventories 103.9

Prepaid and other current assets 4.2

Property, plant and equipment 246.2

Other assets 26.0

Accounts payable, trade ( 94.8 )

Accrued and other current liabilities ( 30.8 )

Other liabilities ( 35.5 )

Asset retirement obligations ( 23.9 )

Total identifiable assets acquired and liabilities assumed 271.1

noncontrolling interest ( 2.3 )

Deferred credit - preliminary bargain purchase gain 273.4

For the twelve months ended December 31, 2023, Jamalco contributed $ 150.3 million to our total revenues and a loss of $ 41.1 million to our total earnings.

In connection with the acquisition, the Company incurred approximately $ 1.4 million of transaction costs for the twelve months ended December 31, 2023, which are included in selling, general and administrative expenses on the Consolidated Statements of Operations.

The following unaudited pro forma financial information reflects the results of operations of the Company for the twelve months ended December 31, 2023 and 2022, respectively, as if the acquisition of Jamalco had been completed on January 1, 2022.

This unaudited pro forma financial information has been prepared for informational purposes and is not necessarily indicative of the actual consolidated results of operations had the acquisition been completed on January 1, 2022, nor is the information indicative of future results of operations of the combined companies.

Year ended December 31,

Revenue $ 2,235.1 $ 2,831.0

Earnings $ ( 45.9 ) $ ( 33.1 )

Curtailment of Operations - Hawesville

On June 22, 2022, our subsidiary, Century Aluminum of Kentucky ("CAKY"), issued a Worker Adjustment and Retraining Notification Act ("WARN") notice at its Hawesville, Kentucky aluminum smelter related to a temporary curtailment of plant operations within 60 days as a result of current market conditions, including historically high energy costs and declining London Metal Exchange ("LME") prices.

We have since fully curtailed production at the facility and expect to continue to maintain the plant with the intention of restarting operations when market conditions permit, including energy prices returning to more normalized levels and aluminum prices maintaining levels that can support the on-going costs and capital expenditures necessary to restart and operate the plant.

As the curtailment represents a significant adverse change in the extent and manner in which the Hawesville smelter will be used, we accordingly evaluated the Hawesville asset group for recoverability.

As the carrying value of the Hawesville asset group was determined to not be recoverable based on the estimated undiscounted cash flows expected to be generated over the life of the asset group, an impairment charge of $ 159.4 million was recognized to write down the asset group to its estimated fair value of $ 15.0 million.

We classified the estimated remaining fair value of the long lived assets within Level 3 of the fair value hierarchy as its fair value was determined based on recent comparable transactions with inputs that are not readily observable in the market.

We recognized approximately $ 18.1 million of expense during the year related to wages and severance triggered by our issuance of the WARN notice and excess capacity charges, partially offset by final plant idling activities.

We also recognized a non-cash other postretirement benefits ("OPEB") curtailment gain totaling $ 8.9 million for the year ended December 31, 2022.

Pension and other postretirement benefits to the consolidated financial statements included herein for additional information.

In August 2022, we fully curtailed production at the Hawesville facility and expect to continue to maintain the plant with the intention of restarting operations when market conditions permit, including energy prices returning to more normalized levels and aluminum prices maintaining levels that can support the on-going costs and capital expenditures necessary to restart and operate the plant.

For the year ended December 31, 2023, we incurred curtailment charges of $ 16.6 million, including $ 9.0 million related to excess capacity charges.

These charges were partially offset by income related to scrap and materials sales of $ 1.7 million.

Comparatively, for the year ended December 31, 2022, we recognized an impairment charge of $ 159.4 million, approximately $ 18.1 million of expense during the year related to wages and severance triggered by our issuance of the WARN notice and excess capacity charges, partially offset by final plant idling activities.

We also recognized a non-cash other postretirement

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

benefits ("OPEB") curtailment gain totaling $ 8.9 million.

Pension and other postretirement benefits to the consolidated financial statements included herein for additional information.

Related Party Transactions

15 unchanged sentences

Alumina purchases from Glencore during 2023 were priced based on published alumina and aluminum indices as well as fixed prices.

Glencore Agreement Settlement

In July 2021, we reached a full and final legal settlement agreement with Glencore resolving a dispute related to alumina purchases and, accordingly, recorded a $ 4.0 million settlement loss to Cost of goods sold.

This amount was paid during the fourth quarter of 2021.

Financial contracts with Glencore

5 unchanged sentences

Borrowings under the Facility Agreement are expected to be used for general corporate and working capital purposes of Century and its subsidiaries.

Carbon Credit Repurchase Agreement

On September 28, 2023, our wholly owned subsidiary Nordural Grundartangi ehf ("Grundartangi"), entered into a structured repurchase arrangement with an affiliate of Glencore pursuant to which it sold 390,000 European Union Allowances ("Carbon Credits") at a price of € 82.18 per Carbon Credit, for an aggregate amount of € 32.1 million.

Pursuant to the terms of the transaction, Grundartangi will repurchase the same number of Carbon Credits at a price of € 83.72 per Carbon Credit, for an aggregate amount of € 32.7 million.

On December 18, 2023, the repurchase arrangement was amended to extend the repurchase window and increase the repurchase price to € 85.13 per Carbon Credit, for an aggregate amount of € 33.2 million.

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

December 18, 2023, Grundartangi sold an additional 40,000 Carbon Credits at a price of € 69.30 per Carbon Credit and will repurchase the same number of Carbon Credits at a price of € 70.71 per Carbon Credit for an aggregate amount of € 2.8 million.

Given the repurchase element of the agreement, the Company retains substantially all of the remaining benefits of the assets and has accounted for the transaction as a financing arrangement in accordance with Topic 606, Revenue from Contracts with Customers ("ASC 606").

A summary of the aforementioned significant related party sales and purchases for the years ended December 31, 2023, 2022 and 2021 is as follows:

5 unchanged sentences

(1) Includes settlements of financial contract positions.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

We disaggregate our revenue by geographical region as follows:

8 unchanged sentences

The amount of consideration we receive, thus the revenue we recognize, is a function of volume delivered, market price of primary aluminum, which is based on the LME, plus regional premiums and any value-added product premiums.

We have also entered into agreements with our customers to sell certain amounts of alumina at market-based prices.

The payment terms and conditions in our contracts vary and are not significant to our revenue.

1 unchanged sentence

Customer payments are due in arrears and are recognized as accounts receivable - net and due from affiliates in our consolidated balance sheets.

In connection with our sales agreement with Glencore, we invoice Glencore prior to physical shipment of goods for a majority of production generated from each of our U.S.

In connection with our sales agreements with certain customers, including Glencore, we invoice the customer prior to physical shipment of goods for a majority of production generated from each of our U.S.

domestic smelters.

For those sales, revenue is recognized only when Glencore has specifically requested such treatment and has made a commitment to purchase the product.

The goods must be complete, ready for shipment and separated from other inventory with control over the goods passing to Glencore.

For those sales, revenue is recognized only when the customer has specifically requested such treatment and has made a commitment to purchase the product.

The goods must be complete, ready for shipment and separated from other inventory with control over the goods passing to the customer.

We must retain no further performance obligations.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Contract liabilities are recorded when cash payments are received or due in advance of performance.

As of December 31, 2023, $ 30.6 million was recorded in Due to affiliates.

There were no contract liabilities as of December 31, 2022.

We are a lessee in various agreements for the lease of office space, land, automobiles, and mobile equipment.

All our leases are considered operating leases.

All of our leases are considered operating leases.

The terms of our leases vary, including the lease term and the ability to renew or extend certain leases.

2 unchanged sentences

Certain lease payment amounts are variable in nature and change periodically based on the local market consumer price index.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

We use our incremental borrowing rate as the basis for the discount rate used to calculate the ROUA and ROUL, respectively, for our operating leases.

3 unchanged sentences

Our ROUA and ROUL balances for the years ended December 31, 2023 and December 31, 2022 were as follows (in millions):

December 31, 2022 December 31, 2021

$ 24.7 $ 20.9

4 unchanged sentences

(2) ROUL - current was recorded as part of Accrued and other current liabilities within Current liabilities at December 31, 2023 and 2022.

(3) ROUL - non-current was recorded as part of Leases - Right of use liabilities within Non-current liabilities at December 31, 2022 and 2021.

(3) ROUL - non-current was recorded as part of Other liabilities within Non-current liabilities at December 31, 2023 and 2022.

The undiscounted maturities of our operating lease liability balances as of December 31, 2023 are as follows (in millions):

3 unchanged sentences

During 2023 and 2022, we entered into new lease obligations, which resulted in $ 3.2 million and $ 1.7 million of additional right of use assets.

We acquired $ 2.4 million of right of use assets related to lease obligations assumed from the Jamalco acquisition.

Total operating expense includes the following (in millions):

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

December 31, 2022 December 31, 2021

Operating leases expense $ 4.9 $ 4.5

1 unchanged sentence

(1) Total lease expense is included in cost of goods sold and selling, general, and administrative expenses on the Consolidated Statements of Operations.

We had cash outflows of $ 4.1 million for amounts included in the ROUL balance at the beginning of the year related to our operating leases for the years ended December 31, 2022 and December 31, 2021.

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

We had cash outflows of $ 4.6 million and $ 4.1 million for amounts included in the ROUL balance at the beginning of the year related to our operating leases for the years ended December 31, 2023 and December 31, 2022, respectively.

Fair Value Measurements

15 unchanged sentences

TOTAL $ 17.0 $ 2.9 $ — $ 19.9

Contingent obligation – net (2)

$ — $ — $ — $ —

Derivative instruments — 7.9 — 7.9

21 unchanged sentences

LME forward financial sales contracts Discounted cash flows Quoted LME forward market

Midwest Premium ("MWP") forward financial sales contracts Discounted cash flows Quoted MWP forward market

Fixed for floating swaps Discounted cash flows Quoted LME forward market, quoted MWP forward market

4 unchanged sentences

ISK/USD forward exchange rate

Heavy Fuel Oil ("HFO") price swaps Discounted cash flows Quoted HFO forward market

When valuing Level 3 assets and liabilities, we use certain significant unobservable inputs.

1 unchanged sentence

Our estimates of significant unobservable inputs are ultimately based on our estimates of risks that market participants would consider when valuing our assets and liabilities.

As of the year ending, December 31, 2023, there were no level three assets and liabilities.

The following table presents the inputs for fair value measurements categorized within Level 3 of the fair value hierarchy, along with information regarding significant unobservable inputs used to value Level 3 assets and liabilities:

5 unchanged sentences

$ — 8.58 % $ ( 2.8 ) 8.58 %

FX Swaps Discounted cash flows Euro/USD forward exchange rate Discount rate net (1)

$ — 8.58 % $ ( 0.2 ) 8.58 %

Nord Pool Swaps Discounted cash flows Quoted Nord Pool forward market Discount rate net (1)

$ — 8.58 % $ 0.2 8.58 %

Casthouse currency hedges Discounted cash flows Euro/USD forward exchange rate;

ISK/USD forward exchange rate Discount rate net (1)

$ — 8.58 % $ — — %

Contingent Obligation Discounted cash flows Quoted LME forward market Expected monthly Hawesville production level (2)

$ — 0 MT/month

$ — 14,000 - 15,000 MT/month

(1) Represents risk adjusted discount rate

(2) Represents management's estimate of expected monthly Hawesville production levels through the term of the agreement in December 2028.

The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis.

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis.

For the twelve months ended December 31, 2022

Level 3 Assets Level 3 Liabilities

Nord Pool Swaps LME forward financial sales contracts LME forward financial sales contracts FX Swaps Casthouse currency hedges

Balance as of January 1, 2022

$ 0.2 $ 0.0 $ ( 5.1 ) $ ( 0.2 ) $ —

Total realized/unrealized gains (losses)

Included in Net Income (1)

— 1.6 5.3 — —

Purchases, sales, settlements

Purchases — — — — —

Sales — — — — —

Settlements — — — — —

Transfers into Level 3 (2)

— 1.7 ( 2.5 ) — 0.0

Transfers out of Level 3 (3)

( 0.2 ) ( 1.5 ) ( 2.3 ) 0.2 0.0

Balance as of December 31, 2022

$ — $ 1.8 $ ( 4.6 ) $ — $ —

Change in unrealized gains (losses) (1)

$ — $ 1.6 $ 5.3 $ — $ —

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

(1) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts."

(2) Transfers into Level 3 due to contracts with applied discount rate entered into during 2022.

(3) Transfer out of Level 3 due to period of time remaining in derivative contract.

For the twelve months ended December 31, 2023

Level 3 Assets Level 3 Liabilities

Nord Pool Swaps LME forward financial sales contracts FX Swaps

LME forward financial sales contracts LME forward financial sales contracts

Balance as of January 1, 2023

$ 1.8 $ ( 4.6 )

Total realized/unrealized gains (losses)

Included in Net Income (1)

— ( 28.7 ) ( 0.6 )

Purchases, sales, settlements

Purchases — — —

Settlements — — —

Transfers into Level 3 (2)

1.7 ( 1.0 ) ( 0.4 )

Transfers out of Level 3 (1)

( 1.5 ) 21.7 0.7

Balance as of December 31, 2023

$ 0.2 $ ( 5.1 ) $ ( 0.2 )

Change in unrealized gains (losses) (2)

$ — $ ( 28.7 ) $ ( 0.6 )

(1) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts."

(2) Transfers into Level 3 due to contracts with applied discount rate entered into during 2021.

(1) Transfer out of Level 3 due to period of time remaining in derivative contract.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

(2) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts."

Debt classified as current liabilities:

2 unchanged sentences

Iceland Revolving Credit Facility (3)

Grundartangi Casthouse Facility (4)

Iceland Term Facility (5)

Vlissingen Facility Agreement (6)

Debt classified as non-current liabilities:

9 unchanged sentences

(3) We incur interest at a base rate plus applicable margin as defined within the agreement.

The interest rate at December 31, 2022 was 7.41 %.

The were no outstanding borrowings at December 31, 2023 .

(4) We incur interest at a base rate plus applicable margin as defined within the agreement.

2 unchanged sentences

The interest rate at December 31, 2023 was 7.05 % .

(6) We incur interest at a fixed rate of 8.75 %.

7.5 % Senior Secured Notes due 2028

1 unchanged sentence

We received proceeds of $ 245.2 million, after payment of certain financing fees and related expenses.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Interest Rate.

5 unchanged sentences

(i) all of our and the Guarantor Subsidiaries' property, plant and equipment (other than certain excluded property);

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

(ii) all equity interests in subsidiaries directly owned by Century or any Guarantor Subsidiaries;

22 unchanged sentences

2.75 % Convertible Notes due 2028

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

On April 9, 2021, we completed a private offering of $ 86.3 million aggregate principal amount of convertible senior notes due 2028 (the "Convertible Notes").

10 unchanged sentences

and structurally junior to all indebtedness and other liabilities (including trade payables) of the Company’s subsidiaries.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Redemption rights.

19 unchanged sentences

revolving credit facility and may be prepaid without penalty.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Status of our U.S.

18 unchanged sentences

In addition, we pay an unused line fee on undrawn amounts, less the amount of our letters of credit exposure.

For standby letters

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

of credit, we are required to pay a fee on the face amount of such letters of credit that varies depending on whether the letter of credit exposure is cash collateralized.

For standby letters of credit, we are required to pay a fee on the face amount of such letters of credit that varies depending on whether the letter of credit exposure is cash collateralized.

Prepayments .

12 unchanged sentences

Under the terms of the Iceland revolving credit facility, when Grundartangi borrows funds it will designate a repayment date, which may be any date prior to the maturity of the Iceland revolving credit facility.

At December 31, 2022, there were $ 35.0 million in outstanding borrowings under our Iceland revolving credit facility.

The Iceland revolving credit facility has a term through November 2024.

At December 31, 2023, there were no outstanding borrowings under our Iceland revolving credit facility.

The Iceland revolving credit facility has a term through December 2026.

Status of our Iceland revolving credit facility:

5 unchanged sentences

Borrowing availability, net of outstanding letters of credit and borrowings 100.0

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Borrowing Base.

6 unchanged sentences

Events of Default.

The Iceland revolving credit facility also includes customary events of default, including nonpayment, loss of license, cessation of operations, unlawfulness, breach of covenant, bankruptcy, change of ownership, certain judgments

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

and certain cross defaults.

Upon the occurrence of an event of default, commitments under the Iceland revolving credit facility may be terminated and amounts outstanding may be accelerated and declared immediately due and payable.

5 unchanged sentences

Interest Rates and Fees .

The interest rate shall be the sum of the interest rate equal to USD LIBOR 3 month plus the applicable margin as set forth in the agreement.

The interest rate shall be at a base rate plus the applicable margin as set forth in the agreement.

Grundartangi shall pay an arrangement fee equal to 0.78 % of the total facility amount, 50 % of which was paid upfront and 50 % to be paid at the end of the availability period, and shall pay a commitment fee of 0.38 % per annum on undrawn commitments, payable quarterly at the same time as interest payments are due and payable.

Upon occurrence of the LIBOR transition, the Casthouse Facility provides for the use of an alternative base interest rate to LIBOR aimed at achieving the same commercial result.

Prepayments .

7 unchanged sentences

Repayments of principal amounts will be made in equal monthly installments, the first payment occurring in February 2023, with the remainder of the principal amount to be paid no later than the termination date in January 2024.

Borrowings under the Iceland Term Facility will bear interest at a rate equal to 3.2 % plus EUR EURIBOR 1 month as published by the European Money Markets Institute.

Borrowings under the Iceland Term Facility will bear

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

interest at a rate equal to 3.2 % plus EUR EURIBOR 1 month as published by the European Money Markets Institute.

As of December 31, 2023, there were $ 1.3 million (€ 1.1 million ) in outstanding borrowings under the Iceland Term Facility.

1 unchanged sentence

On December 9, 2022, Vlissingen entered into a Facility Agreement with Glencore International AG pursuant to which Vlissingen may borrow from time to time up to $ 90 million (the “Vlissingen Facility Agreement”) in one or more loans payable on December 2, 2024, the maturity date of the Facility Agreement.

As of December 31, 2022, there were no outstanding borrowings under the Vlissingen Facility Agreement.

As of December 31, 2023, there was $ 10.0 million in outstanding borrowings under the Vlissingen Facility Agreement.

Vlissingen’s obligations under the Vlissingen Facility Agreement are secured by liens on the ground lease on which Vlissingen’s facilities are located, Vlissingen’s moveable assets, financial assets, receivables and other assets, and Vlissingen’s shares.

1 unchanged sentence

Any amounts outstanding under the Vlissingen Facility Agreement will bear interest at a fixed interest rate equal to 8.75 % per annum and payable on December 2, 2024

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Any outstanding borrowings may be prepaid without penalty or premium in whole or in part without any charge, fee premium or penalty.

16 unchanged sentences

The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock which are currently outstanding, including our Series A Convertible Preferred Stock, or which we may designate and issue in the future.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Preferred Stock

3 unchanged sentences

In addition, issuance of any shares of preferred stock with voting powers may dilute the voting power of the outstanding common stock.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Series A Convertible Preferred Stock

6 unchanged sentences

Our Series A Convertible Preferred Stock has a par value of $ 0.01 per share.

The Common and Preferred Stock Activity table below contains additional information about preferred stock conversions during 2022, 2021 and 2020:

Common and Preferred Stock Activity:

Preferred Stock Common stock

(in shares) Series A Convertible Treasury Outstanding

Balance as of December 31, 2019 67,323 7,186,521 89,185,661

Conversion of convertible preferred stock ( 3,734 ) — 373,416

Issuance for share-based compensation plans — — 496,720

Balance as of December 31, 2020 63,589 7,186,521 90,055,797

Conversion of convertible preferred stock ( 5,047 ) — 504,596

Issuance for share-based compensation plans — — 671,218

Balance as of December 31, 2021 58,542 7,186,521 91,231,611

Conversion of convertible preferred stock ( 4,688 ) — 468,785

Issuance for share-based compensation plans — — 623,582

Balance as of December 31, 2022 53,854 7,186,521 92,323,978

Dividend Rights.

5 unchanged sentences

Upon any liquidation, dissolution, or winding-up of Century, the holders of shares of Series A Convertible Preferred Stock are entitled to receive a preferential distribution of $ 0.01 per share out of the assets available for distribution.

In addition, upon any liquidation, dissolution or winding-up of Century, if our assets are sufficient to make any distribution to the holders of the common stock, then the holders of shares of Series A Convertible Preferred Stock are also entitled to share ratably with the holders of common stock in the distribution of Century’s assets (as though the holders of Series A Convertible Preferred Stock were holders of that number of shares of common stock into which their shares of

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Series A Convertible Preferred Stock are convertible).

However, the amount of any such distribution will be reduced by the amount of the preferential distribution received by the holders of the Series A Convertible Preferred Stock.

3 unchanged sentences

The Series A Convertible Preferred Stock automatically converts, without any further act of Century or any holders of Series A Convertible Preferred Stock, into shares of common stock, at a conversion ratio of 100 shares of common stock for each share of Series A Convertible Preferred Stock, upon the occurrence of any of the following automatic conversion events:

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

• If we sell or issue shares of common stock or any other stock that votes generally with our common stock, or the occurrence of any other event, including a sale, transfer or other disposition of common stock by Glencore, as a result of which the percentage of voting stock held by Glencore decreases, an amount of Series A Convertible Preferred Stock will convert to common stock to restore Glencore to its previous ownership percentage;

14 unchanged sentences

Stock Repurchase Program

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

In 2011, our Board of Directors authorized a $ 60.0 million stock repurchase program and during the first quarter of 2015, our Board of Directors increased the size of the program by $ 70.0 million.

3 unchanged sentences

Shares of common stock repurchased are recorded at cost as treasury stock and result in a reduction of shareholders’ equity in the consolidated balance sheets.

From time to time, treasury shares may be reissued as contributions to our employee benefit plans and for the conversion of preferred stock.

From time to time, treasury shares may be reissued as contributions to our employee

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

benefit plans and for the conversion of preferred stock.

When shares are reissued, we use an average cost method for determining cost.

11 unchanged sentences

Land and improvements $ 105.1 $ 39.8

Mineral Reserves 57.6 —

Buildings and improvements 328.8 305.7

2 unchanged sentences

2,232.5 1,899.8

Less accumulated depreciation ( 1,155.4 ) ( 1,100.4 )

Less accumulated depreciation, amortization and depletion ( 1,228.3 ) ( 1,155.4 )

Property, plant and equipment - net $ 1,004.2 $ 744.4

For the years ended December 31, 2022, 2021 and 2020, we recorded depreciation and amortization expense of $ 73.4 million, $ 82.6 million, and $ 83.0 million, respectively.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

For the years ended December 31, 2023, 2022 and 2021, we recorded depreciation, amortization and depletion expense of $ 74.7 million, $ 73.4 million, and $ 82.6 million, respectively.

Accumulated Other Comprehensive Loss ("AOCL")

1 unchanged sentence

Defined benefit plan liabilities $ ( 101.8 ) $ ( 98.0 )

Unrealized gain (loss) on financial instruments 1.7 1.9

Unrealized gain on financial instruments 1.6 1.7

Other comprehensive loss before income tax effect ( 100.2 ) ( 96.3 )

4 unchanged sentences

Unrealized loss on financial instruments ( 0.3 ) ( 0.3 )

( 0.3 ) ( 0.4 )

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

The following table summarizes the changes in the accumulated balances for each component of AOCL:

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Reclassifications out of AOCL were included in the consolidated statements of operations as follows:

Year Ended December 31,

AOCL Components Location 2023 2022 2021

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Effective January 1, 2018, non-union retiree medical and life insurance benefits are restricted to current participants who meet the eligibility criteria as of January 1, 2018.

Additionally, effective January 1, 2019, Century will no longer administer non-union retiree medical, prescription drug, dental, or vision benefits and instead will make fixed health reimbursement account contributions.

Additionally, effective January 1, 2019, Century no longer administers non-union retiree medical, prescription drug, dental, or vision benefits and instead makes fixed health reimbursement account contributions.

CENTURY ALUMINUM COMPANY

8 unchanged sentences

Interest cost 14.0 10.3 3.8 2.9

Plan amendments 1.1 — — —

Actuarial (gain) loss 10.1 ( 87.7 ) 4.5 ( 23.2 )

3 unchanged sentences

Benefit obligation at end of year $ 271.8 $ 263.0 $ 75.7 $ 73.7

The decreases in both the defined benefit plans' and OPEB plans' benefit obligation were mainly driven by the actuarial gains in 2022, which were primarily attributable to the increases in the discount rates from fiscal year 2021 to 2022.

The increases in both the defined benefit plans' and OPEB plans' benefit obligation were mainly driven by the interest cost and actuarial losses in 2023, which were primarily attributable to the increases in the discount rates from fiscal year 2022 to 2023.

2023 2022 2023 2022

6 unchanged sentences

Fair value of assets at end of year $ 224.8 $ 216.6 $ — $ —

The decrease of actual return on plan assets in 2022 was primarily attributable to fluctuations in market prices during the year.

The change in actual return on plan assets in 2023 was primarily attributable to fluctuations in market prices during the year.

2023 2022 2023 2022

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Total benefit cost $ 7.4 $ ( 5.3 ) $ ( 1.9 ) $ 4.1 $ ( 5.8 ) $ 1.7

(1) During the third quarter, we re-measured certain other postretirement benefits triggered by the Hawesville smelter curtailment, leading to a non-cash OPEB curtailment benefit totaling $ 8.9 million for the year ended December 31, 2022.

(1) During 2022, we re-measured certain other postretirement benefits triggered by the Hawesville smelter curtailment, leading to a non-cash OPEB curtailment benefit totaling $ 8.9 million for the year ended December 31, 2022.

Other changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Loss (pre-tax):

2 unchanged sentences

Net loss (gain) $ 4.4 $ 29.0 $ 4.5 $ ( 23.1 )

Prior service cost (benefit) 1.2 — — —

Amortization of net loss, including recognition due to settlement ( 6.0 ) ( 3.5 ) ( 0.2 ) ( 1.4 )

3 unchanged sentences

Total recognized in net periodic benefit cost and other comprehensive loss $ 6.9 $ 20.1 $ 8.4 $ ( 20.0 )

Weighted average assumptions used to determine benefit obligations at December 31:

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

Weighted average assumptions used to determine benefit obligations at December 31:

2023 2022 2023 2022

2 unchanged sentences

Rate of compensation increase (2)

3.5 % 4 %/ 3.5 %

Measurement date 12/31/2023 12/31/2022 12/31/2023 12/31/2022

9 unchanged sentences

(1) We use the Ryan Above Median Yield Curve to determine the discount rate.

(2) For 2023, the rate of compensation increase is 4.0 % per year for the first year and 3.5 % per year thereafter.

For 2022 and 2021, the rate of compensation increase is 3.0 % per year for the first year and 3.5 % per year thereafter.

46 unchanged sentences

• Diversify the Pension Plans’ equity exposure by investing in real assets that exhibit a low correlation to equities, thereby lowering the overall return volatility of the entire investment portfolio.

• Maintain a diversified exposure within the real asset markets through the use of multi-manager portfolio strategies targeting listed and unlisted exposures.

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

• Maintain a diversified exposure within the real asset markets through the use of multi-manager portfolio strategies targeting listed and unlisted exposures.

• Achieve returns in excess of passive indexes through the use of active investment managers and strategies.

12 unchanged sentences

The following summarizes the Company’s Pension Plans' assets fair value by asset category:

As of December 31, 2022 Level 1 Level 2 Level 3 Assets measured at NAV Total

As of December 31, 2023

Level 1 Level 2 Level 3 Assets measured at NAV Total

Cash and cash equivalents $ — $ — $ — $ 4.6 $ 4.6

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Though the Company believes the methods used to estimate fair value are consistent with those used by other market participants, the use of other methods or assumptions could result in a different estimate of fair value.

Our other postretirement benefit plans are unfunded.

We fund these benefits as the retirees submit claims.

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

Our other postretirement benefit plans are unfunded.

We fund these benefits as the retirees submit claims.

Pension and OPEB Cash Flows

101 unchanged sentences

This cost will be recognized over a weighted average period of 1.8 years.

Earnings (Loss) Per Share

Earnings Per Share

Basic EPS amounts are calculated by dividing net income (loss) allocated to common stockholders by the weighted average number of common shares outstanding.

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(in millions)

Net loss $ ( 14.1 )

Net loss attributable to Century stockholders $ ( 43.1 )

Amount allocated to common stockholders 100 %

4 unchanged sentences

(in millions)

Net loss $ ( 167.1 )

Net loss attributable to Century stockholders $ ( 14.1 )

Amount allocated to common stockholders 100 %

4 unchanged sentences

(in millions)

Net loss $ ( 123.3 )

Net loss attributable to Century stockholders $ ( 167.1 )

Amount allocated to common stockholders 100 %

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State deferred benefit ( 0.1 ) — —

Foreign deferred tax expense (benefit) 43.5 ( 30.5 ) ( 5.9 )

Total deferred expense (benefit) 43.2 ( 30.7 ) ( 7.1 )

Total income tax expense (benefit) $ 47.4 $ ( 30.6 ) $ ( 3.1 )

Foreign deferred tax (benefit) expense ( 30.5 ) 43.5 ( 30.5 )

Total deferred (benefit) expense ( 30.9 ) 43.2 ( 30.7 )

Total income tax (benefit) expense $ ( 14.6 ) $ 47.4 $ ( 30.6 )

A reconciliation of the statutory U.S.

Federal income tax rate to the effective income tax rate on income (loss) is as follows:

Year Ended December 31,

2023 2022 2021

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Helguvik investment — — 26.4

Foreign restructuring — — ( 2.3 )

Foreign dividends and inclusions ( 12.7 ) 122.9 ( 10.1 )

Net operating loss expiration and remeasurement ( 8.0 ) 43.1 ( 5.2 )

Provision to return ( 19.1 ) ( 0.1 ) ( 0.4 )

Filing differences 0.6 ( 19.1 ) ( 0.1 )

Changes in uncertain tax reserves ( 1.3 ) ( 5.3 ) 1.3

Advanced Manufacturing Production Credit 18.6 — —

Other ( 2.7 ) ( 0.9 ) ( 0.2 )

Effective tax rate 21.8 % 142.0 % 15.5 %

The effective tax rate for the year ending December 31, 2022 was higher than the statutory US tax rate of 21% primarily as a result of the calculated foreign inclusions having a greater impact in comparison to the consolidated pre-tax income generated.

The Company’s accounting policy with respect to releasing income tax effects from accumulated other comprehensive income is to apply a security by security approach whereby the tax effects are measured based on the change in the unrealized gains or losses reflected in other comprehensive loss.

The Inflation Reduction Act of 2022 ("IRA") was signed into law on August 16, 2022, and the CHIPS and Science Act of 2022 was signed into law on August 9, 2022.

These laws, effective January 1, 2023, implement new tax provisions, primarily a 15% corporate alternative minimum tax and a nondeductible 1% excise tax on the fair market value of stock repurchased by publicly traded corporations.

As of December 31, 2022, we do not anticipate any material impact of these provisions.

The IRA provides several tax incentives to promote clean energy and the production of critical minerals in the U.S., also effective January 1, 2023.

Century will continue to evaluate potential tax benefits available under the acts as additional guidance is issued in future periods.

The effective tax rate for the year ending December 31, 2023 was 21.8 % compared to the statutory US tax rate of 21%.

The increase is primarily a result of the calculated foreign inclusions, partially offset by the non-taxable benefit of the Advanced Manufacturing Credit under Section 45X discussed below.

In August 2022, President Biden signed the IRA into law.

The IRA provides several tax incentives to promote clean energy and the production of critical minerals in the U.S., including a refundable tax credit, pursuant to Section 45X of the Internal Revenue Code.

Tax credits, such as refundable credits whose realization does not depend on the entity’s generation of taxable income like the refundable tax credit provided by the IRA are not considered an element of income tax accounting under ASC 740.

After considering US GAAP, the Company has concluded it is appropriate to apply IAS 20, Accounting for Government Grants and Disclosure of Government Assistance , to account for the refundable tax credit as an income grant.

Section 45X of the IRA contains a production tax credit equal to 10% of certain eligible production costs, including, without limitation, labor, energy, depreciation and amortization and overhead expenses.

On December 14, 2023, the U.S.

Department of the Treasury and the Internal Revenue Service released proposed rules to provide guidance on the production tax

CENTURY ALUMINUM COMPANY

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(amounts in millions, except share and per share amounts)

credit requirements under Internal Revenue Code Section 45X (the “Proposed Regulations”).

The Proposed Regulations provide guidance on rules that taxpayers must satisfy to qualify for the Section 45X tax credit.

For the year ended December 31, 2023, we recognized $ 56.5 million as a reduction in Cost of goods sold and $ 2.8 million as a reduction in Selling, general and administrative expenses on the Consolidated Statements of Operations and recorded an equal amount as a Manufacturing credit receivable on the Consolidated Balance Sheets.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740):

Improvements to Income Tax Disclosures ("ASU 2023-09").

ASU 2023-09 enhanced annual disclosures regarding the rate reconciliation and income taxes paid information.

For public business entities, ASU 2023-09 is effective for annual periods beginning after December 15, 2024.

The Company is evaluating the impact of this guidance on its consolidated financial statements and related disclosures.

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.

2 unchanged sentences

Accrued postretirement benefit cost $ 30.7 $ 25.7

Net operating losses and tax credits 395.8 453.1

Net operating losses 467.6 395.8

Disallowed interest expense 29.2 27.7

18 unchanged sentences

We have a valuation allowance of $ 537.6 million recorded against our net U.S.

deferred tax assets, and a portion of our Icelandic deferred tax assets as of December 31, 2022.

and Jamaican deferred tax assets, and a portion of our Icelandic deferred tax assets as of December 31, 2023.

The Company is subject to the provisions of ASC 740-10, Income Taxes, which requires that the effect on deferred tax assets and liabilities of a change in tax rates be recognized in the period the tax rate change was enacted.

The increase in deferred tax assets, and the related valuation allowances, is primarily related to the impairment charge recognized to write down the Hawesville asset group to its estimated fair value following curtailment, which was offset by an increase in deferred tax liabilities primarily related to the Company's hedging derivatives.

The change in net operating losses, fixed asset book over tax basis, and the related valuation allowances, were the result of purchase accounting adjustments related to the acquisition of Jamalco, which was offset by a decrease in deferred tax liabilities primarily related to the Company's hedging derivatives.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

The changes in the valuation allowance are as follows:

Year Ended December 31,

2023 2022 2021

5 unchanged sentences

Ending balance, valuation allowance $ 537.6 $ 487.9 $ 485.8

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

The significant components of our NOLs are as follows:

1 unchanged sentence

1,221.0 1,182.7

(1) The federal NOL begins to expire in 2028.

(2) The state NOLs begin to expire in 2027.

(3) The Icelandic NOLs expire between 2023 and 2026.

Foreign (3)(4)

(1) US federal NOLs begin to expire in 2028.

(2) US state NOLs begin to expire in 2027.

(3) NOLs in Iceland expire between 2024 and 2026.

(4) NOLs in Jamaica do not expire.

Our ability to utilize our deferred tax assets to offset future federal taxable income may be significantly limited if we experience an "ownership change" as defined in the Code.

16 unchanged sentences

federal jurisdiction, various state and local jurisdictions, and several foreign jurisdictions.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Our federal income tax returns have been reviewed by the IRS through 2010.

2 unchanged sentences

Accordingly, our 2008 and later NOLs may be reviewed until they are used or expire.

Material state and local income tax matters have been concluded for years through 2016.

Our Icelandic tax returns are subject to examination beginning with the 2017 tax year.

We are subject to examination by tax authorities according to statutory periods defined in each jurisdiction.

The earliest statutory period open is beginning in 2018.

Commitments and Contingencies

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

We have pending against us or may be subject to various lawsuits, claims and proceedings related primarily to employment, commercial, stockholder, environmental, safety and health matters and are involved in other matters that may give rise to contingent liabilities.

19 unchanged sentences

We historically elected to defer certain payments under the PBGC Settlement Agreement and provided the PBGC with the appropriate security.

On October 1, 2021, we amended the PBGC Settlement Agreement (the "Amended PBGC Settlement Agreement") such that we removed the deferral mechanism and agreed to contribute approximately $ 2.4 million per year to our defined benefit pension plans for a total of approximately $ 9.6 million, over four years beginning o n November 30, 2022 and ending on November 30 , 2025, subject to acceleration if certain terms and conditions are met in such amendment.

As of December 31, 2022, we made contributions of $ 2.4 million related to the Amended PBGC Settlement Agreement.

Power Commitments and Contingencies

Hawesville has a power supply arrangement with Kenergy and EDF Trading North America, LLC (“EDF") which provides market-based power to the Hawesville smelter.

Under this arrangement, the power companies purchase power on the open market and pass it through to Hawesville at Midcontinent Independent System Operator ("MISO") pricing plus

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

transmission and other costs.

The power supply arrangement with Kenergy has an effective term through December 2023.

The arrangement with EDF to act as our market participant with MISO has an effective term through May 2023.

On April 26, 2022, EDF gave notice that it would no longer serve as the MISO Market Participant for Hawesville.

The notice terminated EDF's contract, effective May 31, 2023, to purchase power from MISO for resale to Kenergy, which then resells the power to Hawesville.

Century is in discussions with other companies, currently authorized as MISO Market Participants, to replace EDF and expects to have a replacement Market Participant in place prior to the expiration of the contract with EDF.

In connection with the temporary curtailment of production at Hawesville, energy use at the smelter has been significantly reduced.

However, such reduction in energy use does not reduce Hawesville's capacity payment obligation to MISO which extends through May 2023.

Sebree has a power supply arrangement with Kenergy and EDF which provides market-based power to the Sebree smelter.

Similar to the arrangement at Hawesville, the power companies purchase power on the open market and pass it through to Sebree at MISO pricing plus transmission and other costs.

The power supply arrangement with Kenergy has an effective term through December 2023.

The arrangement with EDF to act as our market participant with MISO has an effective term through May 2023.

On April 26, 2022, EDF gave notice that it would no longer serve as the MISO Market Participant for Sebree.

The notice terminated EDF's contract, effective May 31, 2023, to purchase power from MISO for resale to Kenergy, which then resells the power to Sebree.

CASC has a power supply agreement with Santee Cooper that has an effective term from April 1, 2021 and runs through December 2023.

certain terms and conditions are met in such amendment.

As of December 31, 2023, we have made contributions of $ 6.9 million related to the Amended PBGC Settlement Agreement.

Power Commitments and Contingencies

Hawesville has a power supply arrangement with Kenergy and Century Marketer, LLC (“Century Marketer"), Century's wholly-owned subsidiary that acts as a MISO market participant.

Under this arrangement, Hawesville gets access to power at Midcontinent Independent System Operator ("MISO") pricing plus transmission and other costs.

As the MISO Market Participant, Century Marketer purchases power from MISO for resale to Kenergy, which then resells the power to Hawesville.

The power supply arrangement with Kenergy has an effective term through May 2028.

Sebree has a power supply arrangement with Kenergy and Century Marketer, LLC (“Century Marketer"), Century's wholly-owned subsidiary that acts as a MISO market participant.

Under this arrangement, Sebree gets access to power at Midcontinent Independent System Operator ("MISO") pricing plus transmission and other costs.

As the MISO Market Participant, Century Marketer purchases power from MISO for resale to Kenergy, which then resells the power to Sebree.

The power supply arrangement with Kenergy has an effective term through May 2028.

CASC has a power supply agreement with Santee Cooper that has an effective term from January 1, 2024 and runs through December 2026.

Under this power supply agreement, 100 % of Mt.

Holly’s electrical power requirements are supplied from Santee Cooper’s generation at cost of service based rates.

The contract provides sufficient energy to allow Mt.

Holly to produce at 75 % of full production capacity.

Grundartangi has power purchase agreements for approximately 545 MW with HS Orka hf ("HS"), Landsvirkjun and Orkuveita Reykjavikur ("OR") to provide power to its Grundartangi smelter.

12 unchanged sentences

Interest accrues at an annual rate equal to 10.94 % and the term of the agreement is through December 2028.

Based on the LME forward market prices for primary aluminum at December 31, 2023, and current level of Hawesville's operations, including the temporary curtailment, we believe that we will not be required to make payments on the contingent obligation during the term of the agreement, which expires in 2028.

We recognized a derivative asset which offsets our

CENTURY ALUMINUM COMPANY

1 unchanged sentence

(amounts in millions, except share and per share amounts)

Based on the LME forward market prices for primary aluminum at December 31, 2022, and current level of Hawesville's operations, including the temporary curtailment, we believe that we will not be required to make payments on the contingent obligation during the term of the agreement, which expires in 2028.

We recognized a derivative asset which offsets our contingent obligation.

contingent obligation.

As a result, our net liability decreased and we recognized a gain of $ 1.4 million for each of the years ended December 31, 2023 and 2022.

2 unchanged sentences

The following table provides information about the balance sheet location and gross amounts offset:

Offsetting of financial instruments and derivatives Balance sheet location December 31, 2022 December 31, 2021

Offsetting of financial instruments and derivatives Balance sheet location 2023 2022

Contingent obligation – principal Other liabilities $ ( 12.9 ) $ ( 12.9 )

2 unchanged sentences

Labor Commitments

The bargaining unit employees at our Grundartangi, Vlissingen, Hawesville and Sebree facilities are represented by labor unions, representing approximately 59 % of our total workforce.

The bargaining unit employees at our Grundartangi, Vlissingen, Hawesville, Sebree and Jamalco facilities are represented by labor unions, representing approximately 60 % of our total workforce.

Approximately 87 % of Grundartangi’s work force is represented by five labor unions, governed by a labor agreement that establishes wages and work rules for covered employees.

10 unchanged sentences

Holly employees are not represented by a labor union.

Approximately 62 % of Jamalco's work force is represented by the Union of Technical, Administrative, and Supervisory Personnel ("UTASP") through separately labor agreements for hourly and salaried employee groups.

Both contracts are effective through December 31, 2023.

Jamalco is currently in the process of negotiating new contracts with both the salaried and hourly employee groups.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Asset Retirement Obligations

1 unchanged sentence

Year ended December 31,

Beginning balance, ARO liability $ 20.7 $ 19.8

Additional ARO liability incurred 3.8 4.9

Beginning balance $ 21.2 $ 20.7

Additional ARO liabilities incurred 3.1 3.8

ARO liabilities settled ( 1.5 ) ( 4.6 )

Accretion expense 2.0 1.9

Acquired ARO liabilities (See Note 2) 23.9 —

Revisions in estimated cash flows 2.4 ( 0.6 )

Ending balance, ARO liability $ 21.2 $ 20.7

Ending balance $ 51.1 $ 21.2

Current portion of asset retirement obligations (1)

Asset retirement obligations - less current portion $ 49.5 $ 19.6

(1) Current portion of asset retirement obligations is recorded in accrued and other current liabilities.

Business Segments

Century Aluminum is a producer of primary aluminum, which trades as a global commodity.

We are organized as a holding company with each of our operating primary aluminum smelters managed and operated as a separate facility reporting

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

to our corporate headquarters.

Each of our operating primary aluminum smelters meets the definition of an operating segment.

We evaluated the similar economic and other characteristics, including nearly identical products, production processes, customers and distribution and have aggregated our four operating segments into one reportable segment, primary aluminum, based on these factors.

In addition, all of our primary aluminum smelters share several key economic factors inherent in their common products and production processes.

For example, all of our facilities' revenue is based on the LME price for primary aluminum.

Century Aluminum is a producer of primary aluminum, which trades as a global commodity, and owns a 55 % interest in a bauxite mining and alumina refinery joint venture.

We are organized as a holding company with each of our operating primary aluminum smelters managed and operated as a separate facility reporting to our corporate headquarters.

Each of our operating primary aluminum smelters and our bauxite and alumina refinery meets the definition of an operating segment.

We evaluated the similar economic and other characteristics, including nearly identical products, production processes, customers and distribution and have aggregated our five operating segments into one reportable segment, primary aluminum, based on these factors.

In addition, all of our operating segments share several key economic factors inherent in their common products and production processes.

For example, all of our facilities' revenue is based on market pricing.

Our facilities have a similar customer base and utilize similar distribution methods to ship products.

A reconciliation of our consolidated assets to the total of primary aluminum segment assets is provided below.

6 unchanged sentences

the remaining assets are unallocated corporate assets.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

Geographic information

Our net sales are attributed to geographic area based on the location of the selling operation.

Included in the consolidated financial statements are the following amounts related to geographic locations:

5 unchanged sentences

Iceland 529.4 491.0 490.1

Jamaica 275.8 — —

Other 55.1 58.3 61.5

2 unchanged sentences

Major customer information

Revenues from two customers exceeded 10% of our net sales in 2022, 2021 and 2020.

Revenues from one customer in 2023 and two customers in 2022 and 2021 exceeded 10% of our net sales .

A loss of these customers could have a material adverse effect on our results of operations.

6 unchanged sentences

These contracts are expected to settle monthly through December 2024.

We had no open MWP forward financial sales contracts as of December 31, 2022.

We have also entered into financial contracts with various counterparties to offset fixed price sales arrangements with certain of our customers ("fixed for floating swaps") to remain

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

exposed to the LME and MWP aluminum prices.

As of December 31, 2022, we had 946 tonnes related to fixed for floating swaps that will settle monthly through September 2023.

We have entered into financial contracts to hedge a portion of Grundartangi's exposure to the Nord Pool power market (“Nord Pool power price swaps”).

The Nord Pool power price swaps are expected to settle monthly through December 2023.

The Nord Pool power price swaps are settled in Euros, therefore we have entered into financial contracts to hedge the risk of fluctuations associated with the Euro ("FX swaps").

As of December 31, 2022, we had an open position related to the FX swaps of € 32.7 million that will settle monthly through December 2023.

During the third quarter of 2022, we entered certain floating Nord Pool financial contracts to unwind a portion of our fixed contract position as a result of the recent power agreement amendment, making us predominantly hedged against Nord Pool power price fluctuations during 2023.

The pricing relationship between the fixed and floating contracts created a realized gain of $ 16.0 million, which we recognized for the year ended December 31, 2022.

As of December 31, 2022, we had an open net position of 989,880 MWh related to the Nord Pool power price swaps.

We have entered into financial contracts to fix a portion of our exposure to the Indiana Hub power market at our Kentucky plants ("Indiana Hub power price swaps").

As of December 31, 2022, we had an open position of 175,200 MWh.

The Indiana Hub power price swaps are expected to settle monthly through December 2023.

We have entered into forward contracts to hedge the risk of fluctuations associated with the Icelandic Krona (ISK) and Euro for contracts related to the construction of the Grundartangi casthouse denominated in these currencies ("casthouse currency hedges").

As of December 31, 2022, we had an open position related to the ISK casthouse swaps of 5.5 billion ISK that will settle monthly through July 2023.

As of December 31, 2022, we had an open position related to the Euro casthouse swaps of € 8.9 million that will settle monthly through February 2024.

We have also entered into financial contracts with various counterparties to offset fixed price sales arrangements with certain of our customers ("fixed for floating swaps") to remain exposed to the LME and MWP aluminum prices.

As of December 31, 2023, we had 318 tonnes related to fixed for floating swaps that will settle monthly through February 2024.

We previously entered into financial contracts to hedge a portion of Grundartangi's exposure to the Nord Pool power market (“Nord Pool power price swaps”).

The Nord Pool power price swaps are settled in Euros;

therefore, we entered into financial contracts to hedge the risk of fluctuations associated with the Euro ("FX swaps").

During the third quarter of 2022, we entered certain floating Nord Pool financial contracts to unwind a portion of our fixed contract position, making us predominantly hedged against Nord Pool power price fluctuations during 2023.

As of December 31, 2023, we had no open Nord Pool power price swaps.

We previously entered into financial contracts to fix a portion of our exposure to the Indiana Hub power market at our Kentucky plants ("Indiana Hub power price swaps").

As of December 31, 2023, we had no open Indiana Hub power price swaps.

We have entered into forward contracts to hedge the risk of fluctuations associated with the Icelandic Krona (ISK) and Euro for contracts related to the construction of the Grundartangi casthouse and the Sebree casthouse project denominated in these currencies ("casthouse currency hedges").

As of December 31, 2023, we had an open position related to the ISK casthouse swaps of kr 397.0 million and an open position related to the Euro casthouse swaps of € 1.8 million that will settle through January 2024.

We previously entered into financial contracts to hedge a portion of our exposure at our operations to the NYMEX Henry Hub (“NYMEX Henry Hub natural gas price swaps”).

The natural gas volume is measured per million British Thermal Units ("MMBtu").

As of December 31, 2023, we had no open NYMEX Henry Hub natural gas price swaps.

We have entered into financial contracts to hedge a portion of our exposure at our operations to Heavy Fuel Oil (“HFO price swaps”).

The HFO volume is measured per barrel.

As of December 31, 2023, we had an open position of 180,000 barrels.

The HFO price swaps are expected to settle monthly through March 2024.

Our agreements with derivative counterparties contain certain provisions requiring collateral to be posted in the event the market value of our position exceeds the margin threshold limit of our master agreement with the counterparty.

As of December 31, 2022 and December 31, 2021, the Company had recorded restricted cash of $ 0.0 million and $ 8.6 million, respectively, as collateral related to open derivative contracts under the master arrangements with our counterparties.

As of December 31, 2023 and December 31, 2022, we had no recorded restricted cash as collateral related to open derivative contracts under the master arrangements with our counterparties.

The following table sets forth the Company's derivative assets and liabilities that were accounted for at fair value and not designated as cash flow hedges as of December 31, 2023 and 2022, respectively:

1 unchanged sentence

Commodity contracts (1)

$ 2.9 $ 129.1

Foreign exchange contracts (2)

4 unchanged sentences

Total $ 7.9 $ 31.0

(1) Commodity contracts reflect our outstanding LME forward financial sales contracts, MWP forward financial sales contracts, fixed for floating swaps, Nord Pool power price swaps, and Indiana Hub power price swaps.

At December 31, 2022, $ 11.9 million of Due to affiliates and $ 8.3 million of Due to affiliates - less current portion was related to commodity contract liabilities with Glencore.

(1) Commodity contracts reflect our outstanding LME forward financial sales contracts, fixed for floating swaps, Nord Pool power price swaps, HFO price swaps and Indiana Hub power price swaps.

At December 31, 2023, $ 6.4 million of Due to affiliates was related to commodity contract liabilities with Glencore.

At December 31, 2022, $ 11.9 million of Due to affiliates, and $ 8.3 million of Due to affiliates - less current portion was related to commodity contract liabilities with Glencore.

(2) Foreign exchange contracts reflect our outstanding FX swaps and casthouse currency hedges.

CENTURY ALUMINUM COMPANY

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(amounts in millions, except share and per share amounts)

The following table summarizes the net gain (loss) on forward and derivative contracts for the years ended December 31, 2023, 2022, and 2021:

6 unchanged sentences

(1) For the years ended December 31, 2023, 2022, and 2021, $ 0.6 million, $( 13.3 ) million, and $ 116.9 million of net gain (loss), respectively, was with Glencore.

Subsequent events

On January 17, 2023, our wholly owned subsidiary, Mt.

Holly Commerce Park LLC, entered into a binding agreement, subject to ordinary course conditions, to sell approximately 133 acres of land for approximately $ 28.5 million.

We previously formed the commerce park, located near our Mt.

Holly smelter, to develop excess land at the site and to assist the county with bringing additional business and commerce to the area.

Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

1 unchanged sentence

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 8. Financial Statements and Supplementary Data