https://www.google.com/url?rct=j&sa=t&url=http://www.ons.gov.uk/ons/guide-method/method-quality/specific/economy/national-accounts/articles/2011-present/hmrc-vat-update-december-2015.pdf&ct=ga&cd=CAIyGmJjNGEwZWQ4N2QyMGU3Nzg6Y29tOmVuOlVT&usg=AFQjCNF4WNziEW-NPlQypc99JhGaiiDnzg