Published on: August 16, 2025 at 10:44 AM

What is a Surveillance Audit in ISO 27001?

ISO 27001 certification is not a one-time achievement. getting certified is just the beginning. Organizations need to continually demonstrate that their ISMS remains effective. This is ensured through Surveillance Audits.

Surveillance Audits are periodic audits conducted after you’ve obtained your ISO 27001 certification to verify ongoing compliance and continuous improvement. They are less exhaustive than initial certification audits but are crucial for maintaining your certified status.

In this blog, we will explain:

• What is a Surveillance Audit?
• Why Surveillance Audits are Important
• What Happens During a Surveillance Audit
• Common Non-Conformities and How to Avoid Them
• Best Practices to Prepare for Surveillance Audits

What is a Surveillance Audit?

A Surveillance Audit is a mandatory, periodic audit that occurs at least once a year after an organization is ISO 27001 certified. It ensures that the organization’s ISMS continues to meet ISO 27001 requirements and is functioning effectively.

Unlike the initial Certification Audit, which is comprehensive, Surveillance Audits are narrower in scope. The auditor focuses on key processes, risk areas, and continuous improvement efforts.

Surveillance Audits typically cover:

• Selected Annex A controls (as defined in your SoA)
• Changes to the ISMS or organizational structure
• Corrective actions from previous audits
• Compliance with ongoing operational procedures

Why Surveillance Audits are Important

Surveillance Audits are essential for maintaining ISO 27001 certification. They ensure that your Information Security Management System (ISMS) is not just a document but a living system that evolves with your business.

Key reasons why Surveillance Audits are critical:

• Validate that security controls are effectively implemented and maintained
• Ensure compliance with ISO 27001 requirements year-round
• Identify potential non-conformities before they escalate
• Demonstrate ongoing commitment to information security to clients and stakeholders
• Ensure continuous improvement of ISMS processes

What Happens During a Surveillance Audit

External auditors perform Surveillance Audits, generally on an annual basis to verify ongoing compliance. The audit scope is focused but rigorous, ensuring your ISMS is functioning as intended.

The general process includes:

• Audit Planning: The auditor reviews previous audit reports, scope of the ISMS, and prepares an audit plan.
• Opening Meeting: The auditor meets with your leadership to outline the audit’s purpose, coverage, and planned activities.
• Document Review: Policies, procedures, and records are reviewed to check for updates and compliance.
• Process Walkthroughs: The auditor assesses key processes and controls, especially in high-risk areas.
• Interviews: Selected employees are interviewed to ensure awareness and proper execution of ISMS practices.
• Audit Findings: Observations, non-conformities, and suggestions for improvement are documented.
• Closing Meeting: The auditor presents a summary of findings and discusses the next steps.

Common Non-Conformities and How to Avoid Them

During Surveillance Audits, auditors often find recurring non-conformities that organizations can avoid with proactive management.

Common non-conformities include:

• Outdated or incomplete risk assessments
• Missing records of control monitoring and effectiveness checks
• Inadequate documentation of security incidents and corrective actions
• Lack of evidence for employee security awareness training
• Policy documents not aligned with actual business practices. Consider using this Information Security Policy Template.

To avoid these issues:

• Ensure risk assessments are reviewed and updated regularly
• Maintain evidence of control effectiveness through monitoring reports
• Document all security incidents, along with corrective and preventive actions
• Keep updated records of employee training and awareness sessions
• Review and align your ISMS documents with real operational practices

Best Practices to Prepare for Surveillance Audits

Preparation for Surveillance Audits should be a continuous activity. Here are best practices to stay audit-ready:

• Maintain an up-to-date ISMS document repository accessible to key personnel
• ...Conduct internal audits at least annually and address findings proactively.
• Keep your risk assessments current by incorporating new risks and any modifications in business processes.
• Ensure all control implementations have traceable evidence and records
• Track and document all security incidents, including minor ones
• ...Run mock audits or pre-assessments to simulate auditor queries.
• Foster a security-aware culture where employees understand their ISMS responsibilities

Conclusion

Surveillance Audits are not merely a compliance checkbox—they are a vital mechanism to ensure your Information Security Management System (ISMS) remains effective, resilient, and aligned with evolving business needs and threats.

By proactively preparing for Surveillance Audits through regular internal audits, updated documentation, and a culture of continuous improvement, organizations can confidently maintain their ISO 27001 certification.

Staying audit-ready not only safeguards your certification but also strengthens your organization’s overall security posture and builds lasting trust with clients and stakeholders.