Koppers Holdings Inc

(a) Evaluation of Disclosure Controls and Procedures

The Company’s management, with the participation of the Chief Executive Officer and Chief Financial Officer and utilizing the Committee of Sponsoring Organizations of the Treadway Commission (COSO) Internal Control – Integrated Framework (2013), has evaluated the effectiveness of the Company’s disclosure controls and procedures, as defined in Rules 13a-15(e) and 15d-15(e) of the Securities Exchange Act of 1934 as of the end of the period covered by this report. Based on that evaluation, the Chief Executive Officer and Chief Financial Officer have concluded that these controls and procedures were effective as of the end of the period covered by this report.

(b) Changes in Internal Control Over Financial Reporting

In the fourth quarter of 2024, we completed the initial phase of our new enterprise resource planning (ERP) system implementation and migrated our consolidation process onto the new system. As a result, we have implemented updates and changes to our current processes and related control activities. As the phased implementation continues, we will experience certain changes to our processes and procedures which will result in changes to our internal controls over financial reporting. There are inherent risks in implementing an ERP system and, accordingly, Management will continue to evaluate the design and operating effectiveness of these controls.

Except as noted above, there was no change in our internal control over financial reporting (as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) that occurred during our most recent fiscal quarter that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

See Management Report on page 39 for management’s annual report on internal control over financial reporting. See Report of Independent Registered Public Accounting Firm on page 40 for KPMG LLP’s attestation report on internal control over financial reporting.