Internal Audit vs External Audit
Auditing yourself vs being audited by someone outside.
What a comparison is not
A comparison is SPEQ’s reading of how two published documents differ. Neither is the right answer, it is not a determination of which applies to you, and neither is summarised in a way that replaces reading it.
An internal audit (self-inspection) is conducted by the organisation on itself to find and fix problems before others do. An external audit is conducted by an outside party — a customer, a certification/notified body, or a regulator — to verify compliance. Both assess the quality system, but their purpose, independence, and consequences differ.
| ASPECT | INTERNAL AUDIT | EXTERNAL AUDIT |
|---|---|---|
| Who conducts it | The organisation (auditors independent of the area) | Customer, certification body, or regulator |
| Purpose | Find and fix issues internally | Verify compliance / grant certification / enforce |
| Consequence | CAPA; internal improvement | Certificate, purchase decision, or regulatory action |
| Confidentiality | Internal; audit reports often protected | Shared with the auditing party |
| Frequency | Planned, risk-based programme | Per certification cycle, contract, or regulatory schedule |
Run internal audits continuously as your own early-warning system — independent auditors finding gaps so you can fix them before a customer or regulator sees them.
External audits are conducted on you — prepare for them through inspection readiness, and treat their findings as you would any others, but recognise they carry certification or regulatory consequences.
Internal audits are how you find problems; external audits are how others verify you did. A strong internal audit programme is the best preparation for external audits — the issues a regulator or certification body would find should already be in your own CAPA system. Both require auditor independence; the difference is who owns the consequence.
Internal Audit vs External Audit: frequently asked questions
Common questions on how Internal Audit and External Audit differ and when each applies.
What is the difference between an internal and external audit?
An internal audit (self-inspection) is conducted by the organisation on itself to find and fix issues; an external audit is conducted by an outside party — customer, certification/notified body, or regulator — to verify compliance or grant certification. The purpose and consequences differ, but both assess the quality system.
Do internal audits reduce external findings?
That is their value. A rigorous internal audit programme surfaces the issues an external auditor would find, so they are already in CAPA and being remediated. Firms with weak internal audits are the ones surprised by external findings.
What standard governs auditing?
ISO 19011 provides guidelines for auditing management systems (principles, programme management, conducting audits, auditor competence) and applies to both internal and external audits. Sector regulations (GMP self-inspection, ISO 13485) add specific requirements.