Auditors are required to plan and perform an audit with professional skepticism to exercise professional judgement and to comply with ethical standards.
Professional judgement is the application of relevant training, knowledge and experience in making informed decisions about the appropriate courses of action in the circumstances of the audit engagement. The auditor must exercise professional judgement when planning an audit of financial statements.
Professional judgement will be required in many areas when planning. For example, the determination of materiality for the financial statements as a whole and performance materiality levels will require professional judgement. Professional judgement will also be required when deciding on the nature, timing and extent of audit procedures.