VIT34000 | How to treat input tax: transfer of a business as a going concern (TOGC)
From HM Revenue & Customs · VAT Input Tax
The seller of a business can submit a claim for deregistration expenses where:
a business is transferred as a going concern (TOGC); and
the VAT registration number is retained by the purchaser of the business.
The claim is to be submitted in the usual manner on Form VAT 427 - see VIT32000.