This study analyzes the regulatory framework and trust crisis affecting deposit security in Baitul Maal wat Tamwil (BMT) in Indonesia, utilizing a qualitative descriptive approach with a systematic thematic literature review of Scopus-indexed sources. BMT, as an Islamic microfinance institution operating at the intersection of cooperative law and Sharia principles, faces persistent challenges related to regulatory fragmentation, inconsistent Sharia governance, and structural weaknesses that undermine depositor trust. The findings reveal that the absence of a comprehensive, BMT-specific legal framework generates legal ambiguity regarding institutional status—ranging from cooperative to foundation to unincorporated community self-help group—thereby weakening supervisory mechanisms, accountability structures, and deposit protection systems. Unlike formal banking institutions protected by Indonesia Deposit Insurance Corporation (IDIC/LPS), BMTs operating as cooperatives rely solely on internal Ta'awun (mutual assistance) fund principles, which provide insufficient legal protection for depositors. Factors including perceived fund security, institutional transparency, consistency in Sharia principle application, and the presence of a competent Sharia Supervisory Board are identified as the most critical determinants of depositor confidence. Strategic alliances with Islamic banks, integration of Islamic social finance instruments (zakat, waqf, infaq), and fintech adoption emerge as key mechanisms for restoring trust and operational resilience. This study contributes a comprehensive thematic synthesis identifying policy priorities: regulatory harmonization, development of Sharia-compliant deposit insurance, strengthening of Sharia governance, and human resource capacity building. These findings carry significant implications for policymakers, BMT practitioners, and regulatory bodies seeking to ensure the long-term sustainability and inclusiveness of Islamic microfinance in Indonesia.