Which classification level is the highest for personnel clearance?

The highest classification level for personnel clearance is Top Secret. This classification is designated for information that, if disclosed, could cause exceptionally grave damage to national security. Individuals with Top Secret clearance are granted access to the most sensitive information, and there are stringent vetting and investigation processes involved in obtaining this level of clearance.

The other levels of classification, such as Confidential and Secret, are lower levels that represent varying degrees of sensitivity. Confidential is used for information that could cause damage to national security if disclosed, while Secret clearance is for information that could cause serious damage. Restricted is not a standard classification level within the context of personnel clearance in the National Industrial Security Program (NISP) framework and does not align with established security classifications. Understanding the hierarchy of these classifications helps clarify why Top Secret represents the highest tier in terms of personnel clearance.