A codice fiscale is Italy’s tax identification code. It is used as a unique personal identifier in tax administration and many public services, so it can link records to a specific person. Although it is not a password or authentication secret, it is sensitive personal data and should not be treated as harmless simply because it is commonly used for identification.
In digital services, an organization may use codici fiscali to look up or process records-for example, checking whether people can receive messages through a public-service app. Such queries can produce reachability information that may be sensitive when combined, retained, or shared. Defenses include limiting access to authorized staff, sending only the identifiers needed, protecting data in transit and at rest, logging queries, and deleting results when no longer required.