External Audit
An independent assessment conducted by a third-party auditor or certification body to evaluate an organization's compliance with a specific standard or framework, such as ISO 27001 certification audits or SOC 2 examinations.
External audits provide independent, objective assurance that an organization's management system, controls, and processes meet the requirements of a specific standard or framework. Unlike internal audits, external audits are conducted by accredited certification bodies (for ISO certifications) or licensed CPA firms (for SOC 2 examinations). The independence of external auditors gives their findings credibility with customers, partners, regulators, and other stakeholders who rely on the audit results to make trust decisions. External audit results are formalized through certificates (ISO 27001), reports (SOC 2 Type I or Type II), or attestation letters.
The external audit process varies by framework but generally follows a structured approach. For ISO 27001 certification, the process involves a Stage 1 audit (documentation review and readiness assessment) followed by a Stage 2 audit (on-site evaluation of implementation effectiveness). For SOC 2, a Type I examination evaluates the design of controls at a point in time, while a Type II examination evaluates both design and operating effectiveness over a period (typically 6-12 months). NIS2 may require essential entities to undergo regular compliance audits. In all cases, the external audit involves document review, interviews with key personnel, evidence sampling, and testing of controls.
Preparing for an external audit requires significant organizational effort. Organizations should ensure their internal audit program has identified and addressed any nonconformities before the external audit, that documentation is current and accessible, that evidence of control operation is readily available, and that key personnel are prepared to discuss their roles and responsibilities. The external audit may result in nonconformities that must be addressed before certification is granted or within a defined remediation period. Maintaining ongoing audit readiness — rather than scrambling before each external audit — is a hallmark of mature compliance programs and is best achieved through continuous monitoring, regular internal audits, and integrated compliance management.
Related frameworks
Related terms
Audit Evidence
The documented records, observations, test results, and other verifiable information collected during an audit to determine whether the organization's controls and processes conform to the specified requirements and are operating effectively.
Certification Body
An accredited third-party organization authorized to conduct audits and issue certifications confirming that an organization's management system conforms to a specific standard, such as ISO 27001. Certification bodies must be accredited by a national accreditation body to ensure their competence and impartiality.
Internal Audit
A systematic, independent evaluation conducted by an organization's own personnel or contracted auditors to assess the effectiveness of its management system, controls, and processes against defined criteria such as ISO 27001 requirements or internal policies.
SOC 2 Type 1
A SOC 2 audit report that evaluates whether an organization's security controls are suitably designed at a specific point in time. Type 1 provides a snapshot of control design without testing whether controls operate effectively over a period.
SOC 2 Type 2
A SOC 2 audit report that evaluates whether an organization's security controls are both suitably designed and operating effectively over a defined observation period, typically 3 to 12 months. Type 2 is the gold standard for third-party assurance in the US market.
Surveillance Audit
A periodic audit conducted by a certification body between initial certification and recertification to verify that an organization continues to maintain and improve its management system in conformity with the standard. Surveillance audits typically occur annually during the three-year certification cycle.
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