HMRC established a team in April last year, to investigate the use of family investment companies (FICs) amid growing concerns over how the rich exploit loopholes to reduce bills.

In an FIC, members of a family own shares, with parents or grandparents typically exercising control by holding shares with voting rights. By giving shares to children, this can help to reduce inheritance tax liability.

FICs are often used to own assets such as bonds and property, while tax benefits include relief for mortgage interest. Dividends are taxed at corporation tax rates, rather than as income tax, The Times reports.

A Freedom of Information (FOI) request by a public relations company working for the law firm Pinsent Masons revealed the creation of the new HMRC unit.

HMRC told the Financial Times that the division was created to “do a quantitative and qualitative review into any tax risks associated with FICs with a focus on inheritance tax implications”.

Tax experts have said that the declining rate of corporation tax — from 28 per cent in 2008 to 19 per cent today — has made FICs popular.