This study aimed to investigate the moderating role of women's leadership in the audit committee on the relationship between audit quality and tax avoidance in companies listed on the Tehran Stock Exchange. The study is applied in terms of purpose and descriptive-correlational in terms of method and based on retrospective data. The statistical population included all companies listed on the Tehran Stock Exchange during the years 1395 to 1403, and after applying systematic exclusion criteria, 123 companies were finally selected as the final sample. The required data were extracted from financial statements, board of directors' reports, and official databases and analyzed using a multivariate regression model and econometric models. In this study, tax avoidance was measured through the effective tax rate (ETR), audit quality was based on the natural logarithm of audit fees, and women's leadership in the audit committee was measured as a dummy variable (female chairmanship = 1). The results showed that audit quality has a negative and significant relationship with tax avoidance, which indicates the deterrent role of audit oversight in reducing opportunistic tax behaviors. The findings also indicated that female leadership in the audit committee significantly moderates the relationship between audit quality and tax avoidance and causes a change in the intensity of this relationship. The results indicate that the combination of audit oversight quality and gender diversity at key decision-making levels can lead to improved financial transparency and reduced tax risks in companies.