This research investigates the impact of audit firm and audit partner tenure (length of auditor engagement with their client), rotation, specialization, continuing professional education (CPE), and workloads auditor to audit quality with audit committee as a moderating variable. The sample data are the public listed companies in Indonesia from before the rotation regulation period (1999-2001) to after the rotation regulation period (2004-2008).

This research shows that there is a quadratic relationship between the audit tenure and the audit quality. Before regulation period, the relationship between the audit partner and the audit quality is concave (going up until 3 years and then going down) but in the post regulation, the relation is convex (going down in the first 2 years and then going up). The audit firm tenure impact is negative at before regulation, but after regulation is convex (going down for 10 years and then going up). After regulation, audit partner rotation improves the audit quality, however audit firms rotation does not affect the audit quality.

This research found that specialization positively related to the audit quality, workload and CPE negatively related to the audit quality. This research also examines the audit committee as a moderating variable in the quadratic model but does not find the significant relations except for workload.