The Role of High-Reputation Auditors in Mitigating Tax Avoidance Costs in Private Firms with Concentrated Ownership

SUMMARY This paper examines whether high-reputation auditors mitigate costs of tax avoidance in private firms with concentrated ownership. Using detailed data on Norwegian firms from 2000 to 2016, we find that ownership concentration is associated with lower tax avoidance—consistent with controlling shareholders avoiding aggressive tax strategies due to concerns about minority investor perceptions or heightened risk aversion. However, this effect is significantly attenuated when firms engage a Big 4 auditor. The result holds across alternative tax avoidance measures, ownership proxies, firm types and persists under various identification strategies, including matching, auditor switches, and audit-partner mobility. We further show that the effect holds for firms above and below their estimated tax-target and is robust across the tax avoidance distribution. Finally, we find similar effects for industry specialist auditors, suggesting that both brand and domain-specific expertise serve a reputational function. These findings highlight the governance role of external auditors in private firms. JEL Classifications: G32; M42.