Debt and return pursuit: VAT: deregistered customers and revenue losses: unregistered customers
Even if a customer has failed to register and has since ceased to be liable to be registered, it is still possible to claim outstanding tax that arose on or after 6 September 1976 without registering the customer.
Guidance for dealing with such cases is in V1-28, Volume 2, Section 69, which includes telling the customer, by letter, of an assessment of the tax arrears instead of using the usual VAT assessment form.
For unregistered customers (who were not registerable), unpaid penalty assessments cannot legally be classed as VAT, so recovery options include time to pay and civil recovery, but not distress.
(This content has been withheld because of exemptions in the Freedom of Information Act 2000)