If the assignment is a consulting engagement, the best action for the new internal auditor, who recently transferred from being an accounts payable clerk, is to decline the assignment and ask to be reassigned. This avoids any conflict of interest and maintains objectivity, as the auditor would be evaluating processes for which they were previously responsible, potentially compromising the independence and objectivity required in consulting engagements.
IIA Standards 1120 - Objectivity

A significant threat to internal audit objectivity arises when the chief audit executive reports directly to the chief financial officer, especially if the CFO previously led the internal audit activity. This reporting relationship can undermine the independence necessary for objective audits, as the CFO might influence the scope or outcome of audit engagements to suit certain financial reporting outcomes or to cover previous decisions made while in charge of internal audit.
The IIA ' s International Standards for the Professional Practice of Internal Auditing on independence and objectivity.

According to typical descriptions of fraud schemes, Tax evasion (intentional reporting of false or misleading information on a tax return by an organization to reduce taxes owed) and Disbursement fraud (occurs when a person causes the organization to issue a payment for fictitious goods or services) are true statements. These are common schemes that involve intentional misrepresentation to achieve financial gain at the expense of the organization or government.
Fraud examination and prevention literature and standards from professional organizations such as the Association of Certified Fraud Examiners (ACFE) and the Institute of Internal Auditors (IIA).

The best course of action for the auditor in this scenario is to disclose the potential impairment to the customer before accepting the consulting engagement. By doing so, the auditor maintains transparency regarding any conflicts of interest and allows the customer to make an informed decision about the auditor's objectivity. Disclosing prior involvement ensures that both the auditor and the client acknowledge and address any potential bias that could affect the outcomes of the consulting service.
IIA's International Standards for the Professional Practice of Internal Auditing and Code of Ethics.

When a plant manager from within the organization is hired as a rotational internal auditor, the area he should most likely be trained for immediately is risk assessments. This training is crucial because understanding and performing risk assessments is fundamental to the internal audit function, and the plant manager may not have specific skills in this area despite having industry and management experience.
IIA education and training standards