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ISO 9001 Internal Audit Guide

How to run an internal audit that actually finds your gaps — instead of one that just confirms documents exist.

Reviewed by: RASOO Certification Consulting Team · Last reviewed: September 2026
Quick Answer: An ISO 9001 internal audit is a planned, systematic check of whether your QMS conforms to your own documented processes and to the standard, and whether it's genuinely effective — not just present on paper. It's a required step before certification (see our certification process guide) and continues on a planned cycle afterward.

What an Internal Audit Actually Covers

  • Purpose — confirm the QMS conforms to your own requirements and the standard, and that it's effectively implemented and maintained.
  • Audit programme — a planned schedule covering all relevant processes over time, not a single one-off event.
  • Audit scope — which processes, sites, or clauses this specific audit covers.
  • Audit criteria — what you're auditing against (your own procedures, the standard, applicable regulations).
  • Auditor independence — auditors should not audit their own work.
  • Evidence — records, observations, and interviews that support (or contradict) conformity.
  • Findings — conclusions drawn from the evidence, including nonconformities.
  • Nonconformity — a specific instance where a requirement wasn't met.
  • Corrective actions — addressing findings (see our corrective action guide).
  • Audit report — a record of what was audited, what was found, and what happens next.

Common Internal Audit Problems

  • Checking documents only — confirming a procedure exists without verifying it's actually followed.
  • Auditing too superficially — a rushed audit that covers ground but doesn't dig into evidence.
  • No process evidence — relying on interviews alone instead of records, observations, and outputs.
  • Auditor reviewing their own work — undermines the independence the audit is meant to provide.
  • No follow-up — findings recorded but never tracked through to a closed corrective action.

Practical Consultant Note

A genuinely useful internal audit should occasionally make someone uncomfortable — if every internal audit comes back with zero findings, that's usually a sign the audit isn't looking hard enough, not that the QMS is perfect.

If you're heading toward a real certification audit soon, see our audit preparation support for what to have ready.

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Frequently Asked Questions

Who can perform an internal audit?

A: Trained internal staff (as long as they don't audit their own area) or an external party. Small companies sometimes arrange reciprocal audits with a trusted outside resource when internal independence is hard to achieve.

How often is an internal audit required?

A: At planned intervals defined by your own audit programme — the standard doesn't mandate a fixed frequency, but the programme needs to cover all relevant areas over a defined cycle.

Does a finding mean I'll fail certification?

A: No — internal audit findings are meant to be found and fixed before the external audit. Finding nothing is far less reassuring than finding and correctly closing real issues.