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Internal Audit: What It Is, Why You Run One, and Internal vs External Audit
An internal audit is a check an organization runs on itself, to see whether its own processes and records actually meet the standard before anyone from outside examines them. It is the rehearsal for the external audit. The value is in finding the gaps while you still have time and control to fix them.
Why does an internal audit matter?
An internal audit is the cheapest place to find a problem, because the organization catches it before a customer, regulator or external auditor does. Skip it and nonconformities surface during the external audit or in the field, where they cost far more and can put certification at risk. It also gives management real evidence that the quality system works as intended.
Why run an internal audit?
It is the cheapest place to find a problem, because you find it before anyone outside does:
- You catch nonconformities before an external auditor, a customer or a regulator does.
- You test whether the documented process is the process people actually follow.
- You give management real evidence, rather than an assumption, that the system works.
- You build a track record of findings and fixes that certification schemes expect.
- You rehearse, so the external audit holds no surprises.
How does an internal audit differ from an external audit?
It comes down to who runs it, and what the result is for. An internal audit is run by the organization on itself, to improve. An external audit is run by an independent body, to verify and certify. Internal auditors know the business and can dig into causes; external auditors bring the independence that makes a certificate mean something. Run the internal one well and the external audit becomes a formality.
Internal vs external audit at a glance
The rehearsal against the real thing.
| Aspect | Internal Audit | External Audit |
|---|---|---|
| Who runs it | The organization itself | Independent outside body |
| Main purpose | Find and fix early | Verify and certify |
| Independence | Partial | Full |
| Result is for | Management | Customers, regulators |
| Frequency | Set by the organization | Scheduled by the scheme |
Free Internal Audit Checklist
It covers each clause or process area, records whether it conforms, and logs every finding with an owner and a due date, so nothing carries over to the external audit. Download the checklist (PDF). You can also complete the checklist digitally in flowdit on your phone, tablet or PC.
Related Terms
- Root Cause Analysis – closes findings at the source.
- Continuous Improvement Process (CIP) – what audit findings feed.
- Compliance Audit
- ISO 19011
Further Reading
- Best Internal Audit Software 2026
- Audit-Management-Software– plan & run audits
