Guidelines 07/2020 on the concepts of controller and processor in the GDPR

Paragraph 1.3.4  The processor must respect the conditions referred to in Article 28 (2) and  28 (4) for engaging another processor (Art. 28 (3) (d) GDPR).

125. The agreement must specify that the processor may not engage another processor without the controller’s prior written authorisation and whether this authorisation will be specific or general. In case of general authorisation, the processor has to inform the controller of any change of sub-processors under a written authorisation, and give the controller the opportunity to object. It is recommended that the contract set out the process for this. It should be noted that the processor’s duty to inform the controller of any change of sub-processors implies that the processor actively indicates or flags such changes toward the controller. Also, where specific authorisation is required, the contract should set out the process for obtaining such authorisation.

126. When the processor engages another processor, a contract must be put in place between them, imposing the same data protection obligations as those imposed on the original processor or these obligations must be imposed by another legal act under Union or Member State law. This includes the obligation under Article 28 (3) (h) to allow for and contribute to audits by the controller or another auditor mandated by the controller. The processor is liable to the controller for the other processors’ compliance with data protection obligations (for further details on the recommended content of the agreement see section 1.6 below).