IBA: other rules about buildings: parts of buildings
Budget 2007 announced a business tax reform package including the gradual withdrawal of IBAs and ABAs over four years. Legislation was introduced in FA08 to give effect to those changes. The phased withdrawal of IBA writing down allowances had effect for chargeable periods ending on or after 1 April 2008 for businesses within the charge to CT and 6 April 2008 for businesses within the charge to IT. There are no IBA writing down allowances for the financial year beginning on 1 April 2011 and subsequent years.
A building may be used for different activities, some of which would make it an industrial building and some of which would not. If different parts of the building are used for different activities you should look at each part separately in deciding whether IBA is due. The legislation lets you do this because it treats part of a building as a building.
If there is mixed use, that is if all parts of the building are used for all the activities, IBA is given on the whole building provided that the activities that would make it an industrial building are not negligible CA32315.