Audit preparation – Audit preparation consists of everything that is done in advance by interested parties, such as the auditor, the lead auditor, the client, and the audit program manager, to ensure that the audit complies with the client’s objective. The preparation stage of an audit begins with the decision to conduct the audit. Preparation ends when the audit itself begins.
Audit performance – The performance phase of an audit is often called the fieldwork. It is the data-gathering portion of the audit and covers the time period from arrival at the audit location up to the exit meeting. It consists of activities including on-site audit management, meeting with the auditee, understanding the process and system controls and verifying that these controls work, communicating among team members, and communicating with the auditee.
Audit reporting – The purpose of the audit report is to communicate the results of the investigation. The report should provide correct and clear data that will be effective as a management aid in addressing important organizational issues. The audit process may end when the report is issued by the lead auditor or after follow-up actions are completed.
Audit follow-up and closure – According to ISO 19011, clause 6.6, “The audit is completed when all the planned audit activities have been carried out, or otherwise agreed with the audit client.” Clause 6.7 of ISO 19011 continues by stating that verification of follow-up actions may be part of a subsequent audit.
Source : http://asq.org/