Tax analysis: In Knights Developments Ltd, the Upper Tribunal (UT) decided that the trading profits of the taxpayer (KDL), an Isle of Man (IoM) incorporated and resident company, from acquiring, developing and selling UK land were ‘income derived from immovable property’ under art 6 of the 2018 UK-IoM double tax treaty (DTT) (and the corresponding provisions of the amended 1955 DTT). Consequently, the UK retained taxing rights and the UT dismissed the developer’s appeal (made to the First-tier Tax Tribunal (FTT) but transferred to the UT) and upheld the closure notices.