According to IIA guidance, reliable information must be factual, adequate, and convincing to ensure that a prudent and informed person would reach the same conclusions as the internal auditor. This means that the information should be supported by sufficient and appropriate evidence that can be independently verified and substantiated. Reliability of information is crucial for the credibility of audit findings and for making informed decisions based on those findings.

The Institute of Internal Auditors (IIA) Standard 2310 – Identifying Information: "Internal auditors must identify sufficient, reliable, relevant, and useful information to achieve the engagement’s objectives."

IIA Practice Guide on "Audit Evidence"