HMRC have stressed the importance of holding customer data securely.
When calling HMRC's Employer Helpline, you will be required to confirm your Pay As You Earn (PAYE) or Accounts Office reference. These details should be obtained before calling.
If you cannot provide their PAYE or Accounts Office reference, HMRC will give general advice only. If you asks them to tell you the references, they post these to the address held on records.
HMRC are unable to provide the PAYE/Accounts Office reference over the phone following a request for a PAYE registration. Details of the references will be sent by post within 7 days.