Evidence of Industry Scale Effects on Audit Hours, Billing Rates, and Pricing

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.