"The scheme of the 1995 code is to exclude from the expression 'construction of a building' a series of building works. Note (16) deals with these in descending order of their degree of integration with the existing building. Conversions, reconstructions and the alterations of existing building, the most closely integrated, are excluded. Enlargements of existing buildings are then excluded, the word 'enlargement' connoting structural work producing an overall increase in size or capacity. The word 'extension' in relation to an existing building refers, we think, to building work which provides an additional section or wing to that existing building; the degree of integration is one stage less than with enlargements. Then come 'annexes' which, as a matter of principle, are also excluded. The term annexe connotes something that is adjoined but either not integrated with the existing building or of tenuous integration. Annexes intended for use solely for relevant charitable purposes are re-instated into the zero-rated class by Note (17) only if they are capable of functioning independently from the existing building and if both the main access to the annexe is not via the existing building and the main access to the existing building is not via the annexe. Otherwise all annexes are excluded from zero-rating."
"The scheme of Note (16) implies that the construction works falling within paragraphs (a), (b) and (c) are mutually exclusive. Moving down the degrees of integration, if the construction works are found on the facts to produce alterations to the existing building, they will not be works of enlargement or extension; and if they produce an extension, the structure will not be an annexe."
"The two-stage test for determining whether the works carried out constituted an enlargement, extension or annexe to an existing building is well established. It requires an examination and comparison of the building as it was or (if more than one) the buildings as they were before the works were carried out and the building or buildings as they will be after the works are completed; and the question then to be asked is whether the completed works amount to the enlargement of or the extension or construction of an annexe to the original building ( Customs and Excise Commissioners v Marchday Holdings Ltd[1997] STC 272 at 279). I must however add a few words regarding how the question is to be approached and answered, for this has been the subject of some lack of clarity (if not confusion) in a number of the authorities cited to me and it is the failure to approach and answer the question in this case in the correct way which flaws the decision. First the question is to be asked as at the date of the supply. It is necessary to examine the pre-existing building or buildings and the building or buildings in course of construction when the supply is made. What is in the course of construction at the date of supply is in any ordinary case (save for example in case of a dramatic change in the plans) the building subsequently constructed. Secondly the answer must be given after an objective examination of the physical characters of the building or buildings at the two points in time, having regard (inter alia) to similarities and differences in appearance, the layout and how the building or buildings are equipped to function. The terms of planning permissions, the motives behind undertaking the works and the intended or subsequent actual use are irrelevant, save possibly to illuminate the potentials for use inherent in the building or buildings."
"[16] .... The terms of Note (17) indicate that a building may be an annexe to an existing building notwithstanding that it is capable of functioning independently from the existing building and notwithstanding that the only or main access to each of the annexe and the existing building is different. The reference to an 'annexe' in Note (16) when compared with the references to 'enlargement' of or 'extension' to the existing building introduces a different concept. Thus they may be physically separate so that the connection between the two is by way of some other association. But the Tribunal seems to have thought that any association is enough. In my view that cannot be right. If there were a sufficient association between building A and building B, on the Tribunal's conclusion each would be an annexe of the other. So to hold would ignore the plain inferences to be drawn from the use of the word 'annexe'. [17] An annexe is an adjunct or accessory to something else, such as a document. When used in relation to a building it is referring to a supplementary structure, be it a room, a wing or a separate building. The Tribunal does not seem to have given consideration to this, in my view, crucial aspect of an annexe. In that respect their decision is vitiated by a mistake of law and is liable to be set aside."