Amentum Holdings, Inc.

Evaluation of Disclosure Controls and Procedures

Under the supervision and with the participation of our management, including the Chief Executive Officer and the Chief Financial Officer, we conducted an evaluation of the effectiveness of our disclosure controls and procedures (as such term is defined in Rule 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) as of the end of the period covered by this report. Based on this evaluation, our Chief Executive Officer and our Chief Financial Officer concluded that our disclosure controls and procedures were effective as of such date.

Changes in Internal Control Over Financial Reporting

Other than changes related to the integration of a human resources information system and the associated payroll processes following the fiscal year 2024 merger with CMS, there have been no changes 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) during the fiscal quarter ended January 2, 2026 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.