Substantive procedures are intended to create evidence that an auditor assembles to support the assertion that there are no material misstatements in regard to the completeness, validity, and accuracy of the financial records of an entity. Thus, substantive procedures are performed by an auditor to detect whether there are any material misstatements in accounting transactions.
Thus, an auditor who is testing a validity assertion regarding a company's fixed assets could conduct a physical observation of the assets, and then test for record accuracy by evaluating whether there is an asset impairment.
Substantive procedures are included in the audit plan around which an audit is structured. If the results of substantive procedures are not as expected, additional procedures may be added to the audit plan.