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What I should have said is I have not been a customer of Clydesdale bank since 2001
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As mentioned, the destruction of data is phased over time.
If you had remained a customer, the destruction rates would be slowed down and extra remnants of data would have been in their systems. However, when you cease the business relationship, the destruction level is increased.
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and all I wanted to know is do they keep the account numbers and that you were a customer indefinitely
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They don't regurgitate old account numbers. So, that account number is forever allocated to you. So, that bit of data is not something that gets destroyed.
The paperwork for the account would start its destruction sometime after 6 years after repayment of the debt. (maybe extended if you had remained a customer).
i.e. the guidance we have been given under GDPR and the FCA rulebook is that when a client service ends, destruction of non-liability documents should be destroyed after 5 years. However, where the person remains a client, the destruction should be 10 years. Destruction is not required to be instant on an anniversary and can done in phases. And some documents are kept longer than others.
Sometimes, snippets of data can exist which are not personal data but can give a clue. For example, Lloyds Bank had a different account code for loans with PPI and without PPI. So, they can tell from the account number alone if there was PPI on it or not. They know their historic PPi premium rates so can often consider a complaint where no documents exist.
This is why firms all have different periods where data is and is not available.
I am an Independent Financial Adviser (IFA). Comments are for discussion purposes only. They are not financial advice. If you feel an area discussed may be relevant to you, then please seek advice from an Independent Financial Adviser local to you.