COMMUNITY FINANCIAL SYSTEM, INC.

Evaluation of Disclosure Controls and Procedures

The Company maintains 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”), designed to ensure information required to be disclosed by the Company in the reports that it files or submits under the Exchange Act is: (i) recorded, processed, summarized, and reported within the time periods specified in the SEC rules and forms, and (ii) accumulated and communicated to management, including the principal executive and principal financial officers, as appropriate, to allow timely decisions regarding required disclosure. Based on management’s evaluation of the effectiveness of the Company’s disclosure controls and procedures, with the participation of the Chief Executive Officer and the Chief Financial Officer, it has concluded that, as of the end of the period covered by this Quarterly Report on Form 10-Q, these disclosure controls and procedures were effective as of March 31, 2026.

Changes in Internal Control over Financial Reporting

The Company regularly assesses the adequacy of its internal controls over financial reporting. There have been no changes in the Company’s internal controls over financial reporting in connection with the evaluation referenced in the paragraph above that occurred during the Company’s quarter ended March 31, 2026 that have materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting.