Non-doms hold at least £10.9bn in offshore income and gains, of which £4.6bn in income and £6.3bn in gains are neither reported to HMRC nor taxed in the UK, claims a report by University of Warwick and the London School of Economics and Political Sciences (LSE).

This totals £420,000 for each of the 26,000 non-doms who are using the remittance basis charge, which exempts them from UK tax on their foreign income provided it is not brought into the UK. 

The cost of allowing individuals to retain the benefits of non-dom status for the first year remained modest, only reducing total revenue by £210m (7%). However, over three years the tax take was reduced by £860m (27%) and £1.6bn (49%) after five years.