An economic model by DeAngelo shows that the existence of client-specific quasi-rents impairs auditor independence. The provison of non-audit advisory services (NAS) increases quasi-rents, and thus it is a threat to independence. Recently, a number of changes have been made not only to the relevent international and US regulations, but also to the German regulations related to NAS. A large number of empirical studies have investigated the influence of NAS on the perceived auditor independence. Most of these studies were performed in Anglo-Saxon countries, particularly in the US, and a majority found a negative impact. Six studies are based on data from Germany. Most of them failed to find a significant negative impact on auditor's independence. German investors have not been surveyed so far. Thus an empirical investigation of the impact of NAS on investors' perceptions of auditor independence in Germany seemed promising. It was found that shareholders generally perceive a negative effect on auditor's independence if NAS are provided. The effects of 19 different services have been analysed. For most of them a negative effect was found, even if these services are not explicitly prohibited in Germany. Furthermore, it was shown that the type pf NAS influences the degree to which auditor independence is perceived to be impaired. Thus, independence rules related to NAS could be differentiated. Additionally, the study ascertained that perceived auditor independence does increase if NAS are provide by a seperate department of the audit firm.
International Journal of Auditing, 2009, Vol 13, Issue 2, p. 141-161