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, as of March 31, 2024. Based on that evaluation, the Chief Executive Officer and Chief Financial Officer concluded that as of March 31, 2024, the Company’s internal controls were effective to ensure that information required to be disclosed by the Company in reports that it files or submits under the Securities and Exchange Act of 1934 is recorded, processed, summarized, and reported within the time periods specified.

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

The design of any system of controls and procedures is based in part upon certain assumptions about the likelihood of future events. There can be no assurance that any design will succeed in achieving its stated goals under all potential future conditions, regardless of how remote.