This study examines how budget-planning policy is implemented at the Secretariat of the Papuan People's Assembly (Majelis Rakyat Papua, MRP) in South Papua Province and how that planning supports the Assembly's oversight of the Papuan Special Autonomy Fund. Using George C. Edwards III's implementation model (communication, resources, disposition, and bureaucratic structure) as the analytical lens, the study adopted a qualitative descriptive case design drawing on in-depth interviews with five purposively selected informants, field observation, and analysis of the Secretariat's 2025 and 2026 Budget Implementation Documents (DPA). Planning was procedurally compliant, anchored in a layered regulatory hierarchy and executed through formal coordination forums. Substantively, however, the budget fell by about 48% between 2025 and 2026, the dedicated programme supporting the MRP's mandated tasks (Rp6.14 billion in 2025) disappeared from the 2026 DPA, personnel spending rose to 48.5% of the total, and logistics and protocol items expanded sharply. Rigid price standards, information-system constraints, late approvals, staff multitasking, and rented premises compounded these shifts. The findings reveal a decoupling between procedural compliance and oversight capacity, suggesting that Edwards III's variables should be read through the budget as revealed priority. Ring-fenced oversight lines and performance indicators are recommended.