The great-grandson of the chairman of South Africa's De Beers diamond mining company has won his dispute with HMRC over his tax residence.

Jonathan Oppenheimer is a South African citizen born in Johannesburg, but spent much of his youth at school and university in England. When he was 18, his parents bought a London flat, held in trust, for him to use while at college. He then spent some years in South Africa doing national service, after which, in 1993, he went to work for Rothschild Bank in London. He married his US-national wife in England in 1994, and then worked for De Beers in London for a year. Then they moved to Zimbabwe for several years and then to South Africa.

Oppenheimer has always maintained a home in South Africa where his parents live and where he has spent a considerable amount of time. He is a beneficiary of the Harry Oppenheimer Family Continuity Trust, from which he has received large remittances. The Oppenheimer wealth, including his own, is held offshore in terms of ownership.

HMRC's interest in Oppenheimer began in 2007 when the family decided to move to the UK in order to send their children to preparatory school there. They also bought a listed country estate near London and spent around GBP34 million restoring it as a family residence.

In March 2019, HMRC issued him with final closure notices in relation to the tax years 2010/11, 2011/12, 2014/15, 2015/16 and 2016/17, during which it claims Oppenheimer was tax-resident in the UK. Its enquiry, closure notices and associated discovery assessments were predicated on remittances made to him by the family trust during that period, totalling over GBP20 million, resulting in an additional tax assessment of more than GBP10 millon.

Oppenheimer did not dispute that he was resident and ordinarily resident in the UK for the years 2010/11 and 2011/12 under the common law and under the statutory residence test for the years from 2014/15 onwards. However, he also claims that he was resident in South Africa and maintained a permanent home there.

The importance of this relates to the UK's tax treaty with South Africa, which contains...