This manual is supported by the High Inspectorate of Declaration and Audit of Assets (HIDAA). It serves as a critical guide to ensuring compliance with legal standards in public procurement by addressing the prevention, management, and resolution of conflicts of interest. The manual outlines the roles and responsibilities of public agencies and private economic operators, focusing on principles such as transparency, integrity, and equal treatment in procurement procedures. Organized into five chapters, it provides practical examples, legal clarifications, and procedural guidelines for preventing conflicts of interest at all stages of public procurement, thereby supporting both public and private stakeholders in achieving equitable and corruption-free processes.