Customer Due Diligence (CDD) is Primarily procedural assessment that is required when a firm covered by money laundering regulations, ‘enters into a business relationship’ with a customer or a potential customer.
CDD involves identifying the client and verifying their identity on the basis of documents, data or information obtained from a reliable and independent source of the customer identity and profile.
Ref.: http://www.lawsociety.org.uk/support-services/advice/practice-notes/aml/customer-duediligence/