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HMRC internal manual

Capital Allowances Manual

HM Revenue & Customs
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IBA: enterprise zones: meaning of commercial building

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. This phasing out does not apply to EZ WDAs. They continue in full until the cut-off date. There are no IBA writing down allowances for the financial year beginning on 1 April 2011 and subsequent years.


A commercial building is a building that is used for the purposes of a trade, profession or vocation. A building used as an office is also a commercial building.

A building in use as or, as part of a dwelling house is not a commercial building.