COMPASS MINERALS INTERNATIONAL INC

Disclosure Controls and Procedures

Our Chief Executive Officer and Chief Financial Officer have conducted an evaluation of the effectiveness of the design and operation of the Company’s disclosure controls and procedures (as defined in Rule 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934) as amended (the Exchange Act)) under the supervision and with the participation of the Company’s management. Based on that evaluation, the Chief Executive Officer and Chief Financial Officer concluded that as a result of the material weaknesses in internal control over financial reporting as described below in Management’s Report on Internal Controls Over Financial Reporting, the Company’s disclosure controls and procedures were ineffective as of September 30, 2025.

Per Rules 13a-15(e) and 15d-15(e), the term disclosure controls and procedures means controls and other procedures of an issuer that are designed to ensure that information required to be disclosed by the issuer in the reports that it files or submits under the Exchange Act (15 U.S.C. 78a et seq.) is recorded, processed, summarized, and reported within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by an issuer in the reports that it files or submits under the Exchange Act is accumulated and communicated to the issuer’s management, including its Chief Executive Officer and Chief Financial Officer, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure.

Our management, including our Chief Executive Officer and Chief Financial Officer, does not expect that our disclosure controls and procedures or our internal control over financial reporting will prevent all errors and all fraud due to inherent limitations of internal controls. Because of such limitations, there is a risk that material misstatements will not be prevented or detected on a timely basis by internal control over financial reporting. However, these inherent limitations are known features of the financial reporting process. Therefore, it is possible to design into the process safeguards to reduce, though not eliminate, this risk.

In light of the material weaknesses described below, management performed additional analysis and other procedures to ensure that our consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (GAAP). Accordingly, our Chief Executive Officer and Chief Financial Officer have concluded that the Company’s

Consolidated Financial Statements included in this Form 10-K present fairly, in all material respects, our financial position, results of operations and cash flows for the periods presented in conformity with U.S. GAAP.

Management’s Report on Internal Control Over Financial Reporting

The Company’s management is responsible for establishing and maintaining adequate internal control over financial reporting, as defined in Rule 13a-15(f) and 15d-15(f) under the Exchange Act.

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.

A material weakness, as defined in Rule 12b-2 under the Exchange Act, is a deficiency, or combination of control 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 consolidated financial statements will not be prevented or detected on a timely basis.

The Company’s management, with participation of the Chief Executive Officer and Chief Financial Officer, under the oversight of our Board of Directors, evaluated the effectiveness of the Company’s internal control over financial reporting as of September 30, 2025, using the framework in Internal Control - Integrated Framework (2013), issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on that evaluation, management concluded that the Company’s internal control over financial reporting was not effective as of September 30, 2025, due to the material weaknesses in internal control over financial reporting. 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 control deficiencies described above created a reasonable possibility that additional material misstatements to the consolidated financial statements would not be prevented or detected on a timely basis. Therefore, we concluded that the deficiencies represent material weaknesses in the Company’s internal control over financial reporting and our internal control over financial reporting was not effective as of September 30, 2025.

KPMG LLP, the Company’s independent registered public accounting firm, who audited the Company’s consolidated financial statements included in this Annual Report on Form 10-K, issued an adverse opinion on the effectiveness of the Company’s internal control over financial reporting. KPMG LLP’s report is included elsewhere in this Form 10-K.

Remediation Efforts

The material weaknesses identified as of September 30, 2024, noted above were not remediated and the Company determined there were inadequate controls in place to conduct an effective risk assessment process or to effectively identify and assess the controls necessary to ensure reliable information used in financial reporting.

During 2025, we have and are in the process of implementing a number of measures to address the material weaknesses that have been identified including the following:

•We are enhancing our risk assessment process to ensure it is sufficiently robust to identify and analyze all relevant risks of material misstatements, including fraud and the impact of significant changes in the business on the identification of risks and the related impacts to the design of controls.

•We hired additional accounting professionals who possess the requisite technical accounting and internal control over financial reporting knowledge.

•We are educating and training control owners regarding internal control processes and procedures.

•We implemented internal controls to ensure that all journal entries are properly approved, specifically we redesigned and implemented process level control activities over journal entries. We plan to test the operating effectiveness of these controls in the fiscal year ended September 30, 2026.

•We are designing and implementing balance sheet account reconciliation controls, including an approval process and additional process level controls, that includes the appropriate level of precision, support and documentation.

•We are establishing monitoring and oversight controls to identify non-recurring, complex transactions and designing and implementing process level controls to ensure the accuracy and completeness of our financial statements and related disclosures.

•We are in the process of redesigning our corporate organization structure to ensure effective information and communication across the organization and to support financial reporting processes and internal controls.

We will monitor the effectiveness of our remediation measures in connection with our future assessments of the effectiveness of internal control over financial reporting and disclosure controls and procedures, and we will make any changes to the design of our plan and take such other actions that we deem appropriate given the circumstances. We expect to remediate the material weaknesses during the fiscal year ended September 30, 2026.

Changes in Internal Control Over Financial Reporting

Other than the remediation efforts noted above, there was no change in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) that occurred during the fiscal year ended September 30, 2025, that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting. We will continue to take steps to remediate the material weaknesses in our internal control over financial reporting.