Fourth, the Act places important restrictions on audit firms. Historically, public accounting firms earned a large part of their profits by providing consulting services to the companies that they audited. This provided the appearance of a lack of independence because a client that was dissatisfied with an auditor’s stance on an accounting issue might threaten to stop using the auditor as a consultant. To avoid this possible conflict of interests, the act prohibits a public accounting firm from providing a wide variety of nonauditing services to an audit client.