Works to an existing building are normally standard rated. However, where those works result in the creation of an annexe to the existing building and that annexe is to be used solely for a relevant charitable purpose, zero rating is possible.

The annexe must be self-contained and have separate access: see, for example, Treetops Hospice Trust v Revenue & Customs [2011] UKFTT 503 (TC) (25 July 2011) and East Norfolk Sixth Form College v HM Revenue & Customs [2008] UKVAT V20816 (3 October 2008).

For further information on charitable annexes read Chapter 3.25-3.29 of HMRC VAT Notice 708: Buildings and Construction.