The external auditor takes the same steps that a company takes in its internal audits during a formal certification audit.

An opening meeting that will be cover the scope and nature of the audit will be held by the external auditor. Briefings will also be held with the company to discuss audit progress as well as any non-conformities discovered or concerns that have arisen. The auditors will interview employees, and will ask for copies of the companies key EMS documentation, such as the environmental policy, the EMS manual, register of environmental effects, the register of legislation, objectives and targets, etc.

Upon completion of the audit, a closing meeting will be held to discuss any non-conformities discovered. During this meeting, the company will have the opportunity to propose corrective action to the auditor for approval. The company must confirm, in writing, the implementation of any corrective actions taken. The effectiveness of corrective actions taken will be verified during subsequent surveillance audits.

Successful certification will result in the external auditor recommending that the company receive certification. The certificate saying the company is certified to ISO 14001 will usually take two months to arrive.