The rest of the contract could be unsigned if you wish (although there are higher risks associated with registering a written agreement). Must each agreement contain a data clause? No. Only contracts where a flow of data takes place from one party to another and where the relationship between the parties is that of the controller and the processor. Why do I need to know if I am a data controller or a data processor? Unlike the old regime, the GDPR applies to both controllers and processors. .