officially registered
... that it is not compulsory for a place of worship in England and Wales to be officially registered, but doing so makes the premises exempt from Council Tax?
... that it is not compulsory for a <a href="./Place_of_worship" id="mwDTo" rel="mw:WikiLink" title="Place of worship">place of worship</a> in England and Wales to be <b id="mwDTs"><a href="./Places_of_Worship_Registration_Act_1855" id="mwDTw" rel="mw:WikiLink" title="Places of Worship Registration Act 1855">officially registered</a></b>, but doing so makes the premises exempt from <a href="./Council_Tax" id="mwDT0" rel="mw:WikiLink" title="Council Tax">Council Tax</a>?