The task of auditing is the business audit of medium-sized and large corporations (compulsory audit). The subject of the audit is, in particular, the annual financial statements. The result is summarized in an auditor's report. The auditing can also include advice and representation of clients in tax matters.
Tax advice is permitted if the advice only takes up a minor part of the audit. An audit can be carried out by auditors or auditing companies and, in the case of medium-sized companies, by sworn accountants or auditing companies (Section 319 of the German Commercial Code).
The professional principles of the auditing professions are set out in the Wirtschaftsprüferordnung (WPO) and are explained in the statutes of the Wirtschaftsprüferkammer and supplemented internationally by the ISAs (International Standards on Auditing) of the International Federation of Accountants. The international professional organizations of the auditors strive to improve the quality of the examinations through further training. The strict professional obligations also serve as a role model for tax advice (quality assurance).