OLD SECOND BANCORP INC

Evaluation of Disclosure Controls and Procedures

The Chief Executive Officer and Chief Financial Officer have evaluated the effectiveness of the design and operation of the Company’s disclosure controls and procedures, as defined in Rule 13a-15(e) promulgated under the Securities and Exchange Act of 1934, as amended (the “Exchange Act”), as of December 31, 2024. Based on that evaluation, the Chief Executive Officer and Chief Financial Officer concluded that as of December 31, 2024, the Company’s disclosure controls and procedures are effective to ensure that information required to be disclosed by the Company in reports that it files or submits under the Exchange Act is recorded, processed, summarized, and reported within the time periods specified in the SEC’s rules and forms and such information is accumulated and communicated to the issuer’s management, including its principal executive and principal financial officers as appropriate to allow timely decisions regarding required disclosure.

There were no changes in the Company’s internal control over financial reporting during the quarter ended December 31, 2024, that have materially affected or are reasonably likely to materially affect, the Company’s internal control over financial reporting.

Management’s Report on Internal Control Over Financial Reporting

The management of the Company is responsible for establishing and maintaining adequate internal control over financial reporting, as defined in Rule 13a–15(f) under the Exchange Act. The Company’s internal control over financial reporting is a process designed under the supervision of the Company’s Chief Executive Officer and Chief Financial Officer to provide reasonable assurance regarding the reliability of financial reporting and the preparation of the Company’s financial statements for external reporting purposes in accordance with U.S. generally accepted accounting principles.

As of December 31, 2024, management assessed the effectiveness of the Company’s internal control over financial reporting based on the framework established in the “Internal Control - Integrated Framework” issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). Based on this evaluation, management has determined that the Company’s internal control over financial reporting was effective as of December 31, 2024, based on the criteria specified.

Plante & Moran PLLC, the independent registered public accounting firm that audited the consolidated financial statements of the Company included in this Annual Report on Form 10-K, has issued an audit report, included herein, on the Company’s internal control over financial reporting as of December 31, 2024.