The organizational independence of the internal audit activity is most likely to be impaired if the chief audit executive (CAE) reports administratively to the chief financial officer (CFO). Reporting to the CFO can create a conflict of interest and reduce the perceived and actual independence of the internal audit function, as the CFO has direct involvement in financial management and operations, which are common subjects of audits.
This reporting structure could potentially limit the CAE's ability to report issues impartially and independently.References: IIA's International Standards for the Professional Practice of Internal Auditing regarding organizational independence.

The most effective way to ensure that a newly formed internal audit activity remains free from undue management influence is to establish the internal audit activity's position within the organization through an audit charter. According to the Institute of Internal Auditors (IIA) standards, the audit charter should define the purpose, authority, and responsibility of the internal audit activity, clearly outlining the scope of internal auditing within the organization. This foundational document formalizes the internal audit function's role and provides a framework that supports its operational independence.References: The Institute of Internal Auditors (IIA) - International Standards for the Professional Practice of Internal Auditing.

To promote the independence of the internal audit activity, it is required that the chief audit executive reports functionally to the board. This structural alignment helps ensure that the internal audit function is not unduly influenced by management, which might be the subject of audits, and can freely report on its findings and recommendations without fear of reprisal.References: The IIA's International Standards for the Professional Practice of Internal Auditing on independence and objectivity.

The proper drafting and approval of the internal audit charter by the appropriate parties (e.g., the board or audit committee) offer the clearest evidence that the internal audit activity has achieved organizational independence. The internal audit charter formally defines the purpose, authority, and responsibility of the internal audit activity, including its independence from management and its direct reporting line to the board or audit committee. This document is foundational for establishing and maintaining the independence of the internal audit function.
References:
* IIA Standard 1000: Purpose, Authority, and Responsibility
* IIA Standard 1110: Organizational Independence