The auditor's report is a formal opinion, or disclaimer thereof, issued by either an internal auditor or an independent external auditor as a result of an internal or external audit or evaluation performed on a legal entity or subdivision thereof (called an “auditee”). The report is subsequently provided to a “user” (such as an individual, a group of persons, a company, a government, or even the general public, among others) as an assurance service in order for the user to make decisions based on the results of the audit.

An auditor’s report is considered an essential tool when reporting financial information to users, particularly in business. Since many third-party users prefer, or even require financial information to be certified by an independent external auditor, many auditees rely on auditor reports to certify their information in order to attract investors, obtain loans, and improve public appearance. Some have even stated that financial information without an auditor’s report is “essentially worthless” for investing purposes.