Third-Party Assurance Reports in Auditing
Learn how IS auditors use third-party assurance reports to gain confidence over outsourced processes and service provider controls for the CISA exam.
The Need for Third-Party Assurance
Organizations increasingly rely on external service providers for critical business functions, from cloud computing and data processing to payroll management and customer support. IS auditors must evaluate the controls at these service providers, and third-party assurance reports provide an efficient mechanism for obtaining this assurance without conducting direct audits.
Types of Assurance Reports
Several types of assurance reports are available, each serving different purposes and audiences. CISA candidates must understand the distinctions between them and know when each type is appropriate.
SSAE 18 and ISAE 3402 Reports
SOC 1 Reports
SOC 1 reports focus on controls relevant to user entities' financial reporting. These reports are issued under SSAE 18 in the United States and ISAE 3402 internationally. They come in two types:
- Type 1 reports describe the service organization's controls at a specific point in time and provide an opinion on the fairness of the description and suitability of control design
- Type 2 reports cover a period of time, typically six to twelve months, and include testing of the operating effectiveness of controls in addition to design assessment
SOC 2 Reports
SOC 2 reports evaluate controls related to the Trust Services Criteria: security, availability, processing integrity, confidentiality, and privacy. These reports are particularly relevant for IS auditors evaluating cloud service providers and technology outsourcing arrangements.
SOC 3 Reports
SOC 3 reports are general-use reports that provide a summary opinion without detailed control descriptions or test results. They are suitable for public distribution but provide less detail for audit purposes.
Evaluating Third-Party Reports
IS auditors must critically evaluate assurance reports rather than simply accepting them. Key evaluation criteria include verifying the report covers the specific services used by the organization, confirming the reporting period aligns with the audit period, reviewing any exceptions or qualified opinions, and assessing the impact of complementary user entity controls that must be implemented by the organization.
Complementary User Entity Controls
Service organization reports often identify controls that the user entity must implement for the overall control environment to be effective. Auditors must verify these complementary controls are in place and operating effectively, as their absence creates control gaps regardless of the service provider's control effectiveness.
CISA Exam Preparation
For the exam, know the differences between SOC 1, SOC 2, and SOC 3 reports. Understand that Type 2 reports provide greater assurance than Type 1 because they test operating effectiveness over a period. Remember that complementary user entity controls are the organization's responsibility and must be separately verified by the auditor.