COMPASS MINERALS INTERNATIONAL INC

To the Stockholders and the Board of Directors of Compass Minerals International, Inc.:

Opinion on the Consolidated Financial Statements

We have audited the accompanying consolidated balance sheets of Compass Minerals International, Inc. and subsidiaries (the Company) as of September 30, 2025 and 2024, the related consolidated statements of operations, comprehensive (loss) income, stockholders’ equity, and cash flows for the years then ended, and the related notes and the financial statement schedule listed in the Index at Item 15(a)(2) (collectively, the consolidated financial statements). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of September 30, 2025 and 2024, and the results of its operations and its cash flows for the years then ended, in conformity with U.S. generally accepted accounting principles.

We also have 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 September 30, 2025, 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 December 11, 2025 expressed an adverse opinion on the effectiveness of the Company’s internal control over financial reporting.

These consolidated financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on these consolidated financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matters communicated below are matters arising from the current period audit of the consolidated financial statements that were communicated or required to be communicated to the audit committee and that: (1) relate to accounts or disclosures that are material to the consolidated 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 consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

Unrecognized Tax Benefits

As discussed in Note 8 to the consolidated financial statements, the Company recognizes tax benefits from uncertain tax positions only if they are more likely than not to be upheld based on their technical merits. As of September 30, 2025, the Company recorded unrecognized tax benefits of $35.3 million, within other noncurrent liabilities on the consolidated balance sheet, of which a portion related to provincial taxes in Canada.

We identified the evaluation of unrecognized tax benefits for certain provincial tax positions within Canada as a critical audit matter. Specifically, complex auditor judgment and specialized skills and knowledge were required in evaluating the Company’s estimate of the ultimate resolution of these tax positions, inclusive of interest.

The following are the primary procedures we performed to address this critical audit matter. We involved tax professionals with specialized skills and knowledge, who assisted in:

•performing an assessment of certain of the Company’s tax positions for provincial taxes and related interest within Canada and the amount of unrecognized tax benefit, and comparing the results to the Company’s records

•reviewing legal response letters received directly from the Company’s external legal counsel and internal legal counsel that discussed the Company’s unrecognized tax benefit for provincial taxes within Canada

•assessing the qualifications and competence of management and the qualifications, competence and objectivity of external legal counsel

•reviewing the settlement agreement related to this matter between the Company and the Canadian provincial taxing authority.

We assessed the sufficiency of the Company’s disclosures of certain unrecognized tax benefits in Canada included in Note 8.

Sufficiency of Audit Evidence

As discussed in Management’s Report on Internal Control Over Financial Reporting, material weaknesses were identified as of September 30, 2025, across multiple components of the Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. As a consequence of the material weaknesses, internal controls related to the design and operation of process-level controls were determined to be ineffective throughout the Company’s financial reporting processes as of September 30, 2025.

We identified the evaluation of the sufficiency of audit evidence as a critical audit matter. Evaluating the sufficiency of audit evidence obtained required complex auditor judgment because the pervasiveness of the material weaknesses noted above affected substantially all financial statement account balances and disclosures.

The following are the primary procedures we performed to address this critical audit matter. We applied auditor judgment to determine the nature and extent of procedures to be performed over financial statement account balances and we:

•increased the number of sample selections compared to what we would have otherwise made if the Company’s controls were designed and operating effectively,

•tested the underlying records of selected transaction data obtained from the information technology systems to support the use of the information in the conduct of the audit, and

•inspected underlying documentation for a selection of manual and automated journal entries.

We evaluated the sufficiency of audit evidence obtained by assessing the results of procedures performed, including the appropriateness of the nature and extent of such evidence.

/s/ KPMG LLP

We have served as the Company’s auditor since 2023.

Kansas City, Missouri

December 11, 2025

To the Stockholders and the Board of Directors of Compass Minerals International, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated statements of operations, comprehensive income (loss), stockholders' equity and cash flows of Compass Minerals International, Inc. (the Company) for the year ended September 30, 2023, and the related notes and the financial statement schedule listed in the Index at Item 15(a)(2) for the year ended September 30, 2023 (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the results of the Company’s operations and its cash flows for the year ended September 30, 2023, in conformity with U.S. generally accepted accounting principles.

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

/s/ Ernst & Young LLP

We served as the Company’s auditor from 2005 to 2023.

Kansas City, Missouri

November 29, 2023 except for the effects of the restatement discussed in Note 1 and Note 23 to the consolidated financial statements included in the Company’s 2023 Annual Report on Form 10-K/A, as to which the date is October 29, 2024, and except for the effects of the adoption of ASU 2023-07 included in Note 12 to the consolidated financial statements included in the Company’s 2025 Annual Report on Form 10-K, as to which the date is December 11, 2025

To the Stockholders and the Board of Directors of Compass Minerals International, Inc.:

Opinion on Internal Control Over Financial Reporting

We have audited Compass Minerals International, Inc. and subsidiaries’ (the Company) internal control over financial reporting as of September 30, 2025, based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. In our opinion, because of the effect of the material weaknesses, described below, on the achievement of the objectives of the control criteria, the Company has not maintained effective internal control over financial reporting as of September 30, 2025, based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated balance sheets of the Company as of September 30, 2025 and 2024, the related consolidated statements of operations, comprehensive (loss) income, stockholders’ equity, and cash flows for the years then ended, and the related notes and the financial statement schedule listed in the Index at Item 15(a)(2) (collectively, the consolidated financial statements), and our report dated December 11, 2025 expressed an unqualified opinion on those consolidated financial statements.

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 material weaknesses have been identified and included in management’s assessment. The Company, due to a limited allocation of trained, knowledgeable resources, did not conduct an effective risk assessment process to identify and evaluate at a sufficient level of detail all relevant risks of material misstatement, including fraud risks associated with the necessary approval of transactions. Additionally, the Company did not have an effective information and communication process that identified and assessed the source of and controls necessary to ensure the reliability of information used in financial reporting and that ensured complete, reliable information was made available to financial reporting personnel on a timely basis to fulfill their roles and responsibilities. As a consequence of the material weaknesses described above, internal control deficiencies related to the design and operation of process-level controls were determined to be ineffective throughout the Company’s financial reporting processes. The material weaknesses were considered in determining the nature, timing, and extent of audit tests applied in our audit of the 2025 consolidated financial statements, and this report does not affect our report on those consolidated financial statements.

The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management's Report on Internal Control Over Financial Reporting. Our responsibility is to express an opinion on the Company’s internal control over financial reporting based on our audit. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audit also included performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

Definition and Limitations of Internal Control Over Financial Reporting

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; (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; 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.

Disclaimer on Additional Information in Management’s Report

We do not express an opinion or any other form of assurance on management’s statements, included in the accompanying Management's Report on Internal Control Over Financial Reporting, referring to corrective actions taken after September 30, 2025, relative to the aforementioned material weaknesses in internal control over financial reporting.

/s/ KPMG LLP

Kansas City, Missouri

December 11, 2025