The principle of accountability requires you to be able to demonstrate that you are complying with the GDPR, and have appropriate policies and processes. This means that you need to be able to show that you have properly considered which lawful basis applies to each processing purpose and can justify your decision.
You need therefore to keep a record of which basis you are relying on for each processing purpose, and a justification for why you believe it applies. There is no standard form for this, as long as you ensure that what you record is sufficient to demonstrate that a lawful basis applies. This will help you comply with accountability obligations, and will also help you when writing your privacy notices.
It is your responsibility to ensure that you can demonstrate which lawful basis applies to the particular processing purpose.
N.B. By completing the ELR GP Fed DPO self-assessment questionnaire, and receiving your review from the Data Protection Officer, you will fulfil this requirement.
