Where a type of processing in particular using new technologies, and taking into account the nature, scope, context and purposes of the processing, is likely to result in a high risk to the rights and freedoms of natural persons, the controller shall, prior to the processing, carry out an assessment of the impact of the envisaged processing operations on the protection of personal data. A single assessment may address a set of similar processing operations that present similar high risks.

A data protection impact assessment referred to in paragraph 1 shall in particular be required in the case of:

– a systematic and extensive evaluation of personal aspects relating to natural persons which is based on automated processing, including profiling, and on which decisions are based that produce legal effects concerning the natural person or similarly significantly affect the natural person;
– processing on a large scale of special categories of data referred to in Article 9(1) GDPR, or of personal data relating to criminal convictions and offences referred to in Article 10 GDPR; or
– a systematic monitoring of a publicly accessible area on a large scale.

Source: Article 35 GDPR