Purpose
This study aims to examine how new regulation changes for the auditor’s report, so-called key audit matters (KAMs), influence tax avoidance.

Design/methodology/approach
This study uses data from firms listed on the Omani capital market over the period 2012–2019 and analyzes these data using pooled panel data regression with a robust standard error. It uses two common proxies for tax avoidance and two measures for the KAMs disclosure requirement.

Findings
This study finds a sharp decrease in the effective tax rate following the introduction of KAMs disclosure and the issuance of more KAMs in audit reports. This result is supported by several robustness checks. In an additional analysis, the authors observe interesting results, indicating that real earnings management mediates this association, while the audit committee plays a moderating role. The authors do not find a moderating effect of Big4 on this association, but find discrepancies within the Big4 firms in relation to this moderating effect.

Originality/value
The results of this study indicate that although the introduction of the KAMs disclosure requirement may have positive consequences, it may also lead to unintended negative consequences. This conclusion has not been comprehensively reported in literature.