Using a proprietary data set consisting of all private firm audit engagements in 2000 from one Big 4 firm in Belgium, we investigate (i) whether audit office industry scale is associated with a reduction of total, partner, and staff audit hours and thus with efficiency gains triggered by organizational learning from servicing more clients in an industry and (ii) whether the extent of efficiency pass‐on from the auditor to its clients depends on the audit firm's market power. We find that auditor office industry scale is associated with efficiency gains and a reduction of the variable costs (i.e., fewer total audit hours, partner hours, and staff hours), ceteris paribus. Our results also suggest that, on average, realized efficiencies are entirely passed on, as evidenced by a nonsignificant effect of auditor industry scale on the auditor's billing rate. Furthermore, we find that the extent of the efficiency pass‐on decreases with the market power of the audit firm in the industry market segment as we document a higher billing rate for auditors with high market power (versus low market power). In addition, we find that the lower audit hours associated with auditor industry scale do not compromise audit quality.

Competition in audit markets is an important topic but direct tests of market competition have been limited. In this paper, we examine how audit firms behave when they are confronted with competition from another firm in a wide range of industry segments in a local market. Sharing a large number of market segments can lead to mutual forbearance among audit rivals. Such mutual forbearance is likely to manifest as higher audit fees in a market because rivals are hesitant to aggressively compete in the face of potential competitive retaliation. Using a sample of 25,662 observations from 2004 to 2015, we find evidence that supports this argument as proxied by the extent that audit firms compete in the same industries in the same locations. This result persists after controlling for several tight fixed‐effects specifications based on time, location, industry, and market segments. In supplementary tests, we also find that the likelihood of client switching is negatively associated with the multi‐industry contact of the incumbent, but clients that do switch are more likely to choose an alternative audit firm that confronts the predecessor auditor in fewer market segments. Our evidence is consistent with mutual forbearance among rival audit firms when confronted with the same competitor in different market segments.

Economic incentives are fundamental for understanding auditor behavior. In this paper, we investigate the association between the extent of partners' fee-based compensation, partners' observable net wealth, and audit quality. Using a sample of Belgian Big 4 audit firms and their predominantly private clients, our results suggest a negative association between audit quality and partner fee-based compensation, and a positive association between audit quality and partner observable net wealth. Moreover, our results show that the latter association is most significant when a partner is carrying a lot of debt, which indicates that a partner's financial situation may affect audit quality. The extent of fee-based incentives also varies among partners of the same audit firm. Furthermore, partner and client characteristics differ based on the extent of fee-based compensation. Our findings should be of interest to regulators and audit firms, as they suggest that audit partners' economic incentives significantly affect audit quality. Data Availability: All data are publicly available from the sources identified in the text.