VATREC4030 | VAT invoices: requirement to provide invoices: Invoices and VAT groups
From HM Revenue & Customs · VAT Traders’ Records Manual
Under the VAT Act 1994, sections 43 and 44, supplies by one member to another within the same VAT registered group (except on certain self-supplies of stationery) are disregarded for VAT purposes.
Transactions between one division and another of a corporate body registered in the names of its divisions are regarded as outside the scope of VAT
VAT invoices must not be issued in either situation.