(potentially reducing capital gains tax) depends on whether there was improvement of the property: if there was none, it is against income; if there was some, then it is against capital. Transfers between husband and wife or between civil partners do not crystallise a capital gain, but instead transfer the purchase price (book cost). Otherwise, transfers made as gifts are treated for CGT purposes as being made at the market value at the date of transfer. Tax gap The 'tax gap' is the difference between the amount of tax that should, in theory, be collected by HMRC, against what is actually collected. The tax gap for the UK in 2013–14 was £34 billion, or 6.4 percent of total tax liabilities. It can be broken down by tax type and behaviour See also UK-related HM Revenue & Customs Chartered Institute of Taxation Government spending in the United Kingdom Institute of Indirect Taxation Income in the United Kingdom Tax credit Starting rate of UK income tax Economic history of the United Kingdom History of taxation in the United Kingdom Why the United Kingdom income tax year begins on 6 April History of inheritance taxes in the United Kingdom Local taxation Business rates Council tax Local income tax General category Tax Tax haven Tax law References Citations Sources Stephen Dowell, History of Taxation and Taxes in England (Routledge, 2013)