This document is a guide addressing the management of legacy data at the Central KYC Records Registry (CKYCRR) by Reporting Entities (REs). It outlines the significant progress made in digitizing Know Your Customer (KYC) records across India, noting that CKYCRR currently holds approximately 112 crore digitized records. However, it highlights the challenges related to legacy data compliance, emphasizing that the volume of pending legacy data is substantial. The guide details the reasons for compliance gaps, including issues with customer onboarding identifiers and variations in recorded data. It presents a recommended step-by-step process for REs to conduct effective CKYC searches for legacy customers, advocating for a multi-parameter search optimization approach. Additionally, it discusses interim solutions for REs that have not integrated their systems with the CKYC API, such as using an SFTP-based bulk search mechanism. The document concludes by encouraging REs to adopt real-time API integration for improved efficiency.