Is it possible to identify a client through MH-CLD?

No, one of the important features of MH-CLD reporting is its use of non-protected health information (non-PHI). No personal identifying information, as defined under the Health Insurance Portability and Accountability Act (HIPAA) rule for PHI, is reported in the data files. The client-level data files use a unique, non-PHI client ID for reporting the required and optional information on a particular client within and across reporting periods.