The purpose limitation principle requires that personal data be collected for specified, explicit and legitimate purposes and not be further processed in a manner that is incompatible with those purposes. However, the GDPR does not provide a clear definition of what constitutes an incompatible purpose. Instead, it leaves room for interpretation by the member states, taking into account the context and circumstances of the processing. This means that the degree of flexibility a controller has in using personal data for a new purpose may vary depending on the member state’s law and guidance. Some factors that may affect the compatibility assessment include the link between the original and the new purpose, the expectations of the data subject, the nature of the data, the impact of the further processing, and the safeguards applied by the controller. References:

GDPR Article 5(1)(b), which states the purpose limitation principle.

GDPR Article 6(4), which lists the criteria for assessing the compatibility of a new purpose.

ICO guidance, which explains the purpose limitation principle and provides examples of compatible and incompatible purposes.

[EDPB guidelines], which provide further guidance on the application of the purpose limitation principle.