Brief statement
During the late 1990s and early 2000s, non-audit services revenue increased rapidly for all of these firms. Then, non-audit services revenue dropped significantly for the Big Four, due to the bankrupt of Enron and the adoption of the Sarbanes-Oxley Act of 2002 (SOX). From 2003 to 2007, in spite of the drop in non-audit service revenue, increases in assurance service revenue more than made up the difference, resulting in overall revenue increases for all of the firms. However, since 2008, non-audit services revenue has risen again for the Big Four. My individual paper aim is to present the facts and people’s concerns about the non-audit services’ effects on auditor’s independence.

Definitions of Non-audit service and Independence
Non–audit services generally refer to the services above and beyond the related audit services or services other than traditional CPA work. Scholars in their studies use different terms for some relevant issues, namely, “Management Advisory Service“(MAS) and “Management Consulting Service” (MCS). While there is no particular restriction for the scope or classification of non-audit service, diverse classification methods have been employed by the researchers (Schemer and Kiger, 1982; Pany and Rechkers, 1983). Purcell and Lifison (2003) defined non-audit services as traditional CPA works (including assurance, investment assurance, and commerce registration and accounting affairs, and so on), as well as, tax advisory service, management advisory service, finance and investment advisory service, and information technology advisory service.
The fundamental concept of professional independence is an attitude of the mind based on integrity and an objective approach to work. He maintained that an auditor must at all times, perform his research objectively and impartially and free from influence by any consideration which might