Background: Corporate tax avoidance remains a significant challenge in Indonesia’s fiscal system, reflecting managerial discretion and weak corporate governance. While prior studies mainly emphasize firm-level factors, limited research explores how board characteristics shape corporate tax decisions, particularly through earnings management mechanisms.

Objective: This research intends to examine the impact of board diversity, comprising gender diversity, board size, and educational background, on corporate tax avoidance, in addition to investigate the mediating role of earnings management in this relationship

Research Methods: The study uses 417 firm-year observations from 139 publicly listed manufacturing companies on the IDX from 2019-2021. The study utilizes panel data regression to evaluate direct and mediating effects, with firm size and year as control variables. Earnings management is quantified using the Modified Jones Model, while tax avoidance is represented by the Cash Effective Tax Rate (CETR)

Research Results: The findings reveal that gender diversity negatively affects both earnings manipulation and tax reduction, suggesting that female directors enhance ethical financial reporting and compliance. Conversely, educational background exhibits a positive relationship with tax avoidance, implying that financially literate boards may exploit tax planning opportunities. Board size shows no significant effect on either variable. Mediation analysis confirms that earnings management mediates the nexus between gender diversity and tax avoidance, but not for board size or educational background. Furthermore, firm size and the research year, affect earnings management but not tax avoidance.

Originality/Novelty of Research: This study enriches upper echelon theory by integrating behavioral governance perspectives, demonstrating that board diversity influences corporate tax behavior both directly and indirectly through earnings management. The findings provide new insights into how gender diversity enhances ethical decision-making within emerging market governance structures.