Roedd syniad yr Athro Holtham am ardoll gofal cymdeithasol yn un o’r pedwar syniad am drethi newydd a gododd o’r drafodaeth genedlaethol am drethi newydd yn ystod haf 2017. Cyhoeddwyd ei adroddiad a’i ddadansoddiad economaidd ym mis Mehefin 2018.
Professor Holtham’s idea for a social care levy was one of four new tax ideas to emerge from the national debate about new taxes in the summer of 2017. His report and economic analysis was published in June 2018.