In 2004, ASML established an internal audit function. The internal audit function forms one of the key elements to address the topics of risk management and internal control over financial reporting as required under the Dutch Corporate Governance Code and the Sarbanes-Oxley Act respectively. The initial role of the internal audit function was directed at facilitating the implementation of an enhanced (internal) control framework.

From the fourth quarter of 2005 onwards, the internal audit function has taken on its (ultimate) independent audit function. The internal auditor reports to the Board of Management and the Audit Committee. The external auditor and the Audit Committee are involved in drawing up the work schedule and the audit scope of the internal auditor, and shall also take regard of the findings of the internal auditor.