Self-Assessment vs External Audit: When to Use Each

Two Paths to the Same Goal

Both self-assessments and external audits serve the same fundamental purpose: evaluating how well your organisation meets the requirements of a given framework. But they differ in credibility, cost, depth, and use case.

Self-Assessment: The Internal View

A self-assessment is conducted by your own team:or with the help of a toolkit that guides the process. You evaluate your controls, policies, and practices against a framework's requirements and identify gaps.

Best for:

• Initial readiness checks before pursuing certification
• Gap analysis when adopting a new framework
• Internal monitoring between external audits
• Frameworks where certification isn't available or required
• Building compliance capability within your team

Strengths: Fast (days, not weeks), inexpensive, repeatable, builds internal expertise, identifies gaps before external auditors do.

Limitations: Lower credibility with external stakeholders, potential for bias or blind spots, no formal attestation or certificate.

External Audit: The Independent View

An external audit is conducted by an independent, typically accredited party. The auditor reviews evidence, interviews staff, and provides a formal opinion on compliance.

Best for:

• ISO certification (27001, 9001, 22301, etc.)
• SOC 2 Type II reports for customers
• Regulatory requirements that mandate independent assessment
• Demonstrating compliance to investors, customers, or partners

Strengths: Independent verification, formal attestation, higher credibility, may identify issues internal teams miss.

Limitations: Expensive ($15K-$100K+), time-intensive (weeks of preparation), point-in-time view, auditor quality varies.

The Smart Combination

The most effective compliance programmes use both. Self-assess quarterly to maintain continuous awareness of your compliance posture. Use external audits annually for formal certification and stakeholder assurance.

The self-assessment becomes your audit preparation tool:by the time the external auditor arrives, you've already identified and remediated any gaps.