This study explores the harmonization of financial reporting and accounting standards in the merger of two Indonesian state-owned enterprises (SOEs), Perum X and Perum Y. Employing a qualitative case study approach, the research investigates the systemic differences in accounting policies, financial information systems, and reporting structures that pose significant challenges in the post-merger integration process. Data were collected through in-depth interviews, document analysis, and observation of the integration process. The findings reveal disparities in Chart of Accounts (COA) structure, PSAK implementation—particularly PSAK 16 and PSAK 71—and the use of financial systems, with X operating an ERP-based system while Y remains reliant on Excel-based processes. Regulatory interventions, such as asset restatement and capital participation adjustments, are also discussed as critical factors influencing harmonization efforts. A conceptual framework is proposed to guide future SOE mergers in aligning accounting systems and policies. The harmonization process enhances financial transparency, managerial decision-making, and auditability, but also highlights the need for national guidelines and institutional coordination. This study contributes to the literature on public sector accounting by providing practical insights and policy recommendations for improving the consistency and integrity of financial reporting in SOE mergers. It also opens avenues for further research on long-term outcomes and cross-sector comparisons of accounting harmonization in public enterprises.