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

No, it is not possible to identify a client through the Mental Health Client Level Data (MH-CLD). One of the important features of MH-CLD reporting is its use of non-protected health information (non-PHI). No personal identifying information is reported in the data files.

The client-level data files use a unique, non-PHI client ID. This ID is used for reporting any information on a particular client, within and across reporting periods. 

More information on PHI can be found on this Summary of the HIPPA Privacy Rule page.