Abstract This study examines the impact of audit regulation in New Zealand, using audit quality reviews undertaken by the Financial Markets Authority (FMA) between 2013 and 2017. Regulation has more than halved the number of registered audit firms indicating that it imposes costs on audit firms. The results show that audit quality is improving, but a high proportion of audits do not meet the FMA's requirements. A key area for improvement is the consistency of quality across audits performed by the same audit firm. The FMA advises audit firms to investigate the underlying cause of audit deficiencies to ensure that internal quality control systems are effective in producing high‐quality audits on a regular basis. A comparison of audit file ratings with the United Kingdom shows that New Zealand's audit quality is much lower. The variation in audit quality across countries concerns the International Forum of Independent Audit Regulators (IFIAR) as it has the potential to undermine stakeholder confidence in the audit industry. Thus monitoring progress in improving audit quality in New Zealand is important. This paper provides insights into audit quality at a country level, whereas most research focuses on the firm level.