Rachel Reeves should increase capital gains tax (CGT) at Labour’s upcoming Budget, a group of millionaire business owners have urged, estimating the measure would raise £14bn a year.

A Treasury minister rebutted claims that capital gains tax could hit 39 per cent but did not rule out a rise in the Budget. James Murray stressed that a possible jump to 39 per cent was something that he “completely didn’t recognise”.

Britain will increase the rate of capital gains tax payable on sales of shares and other assets in an Oct. 30 budget statement, the Times newspaper reported on Wednesday, saying the increase for share sales was likely to be several percentage points.

Capital gains tax is often called the forgotten levy - but it is unlikely that Chancellor Rachel Reeves will overlook it in her Autumn Budget.

UK Chancellor Rachel Reeves could raise £15 billion ($20 billion) a year from the wealthiest Britons by targeting capital gains and inheritance without triggering an exodus of millionaires, according to two think tank reports.

The Chancellor told ministers on Monday that plans to fill a £22 billion black hole would be enough only to ‘keep public services standing still’.

A group of "patriotic millionaires" have urged Chancellor Rachel Reeves to hike capital gains tax to help raise cash for the Government. Mark Campbell, founder of Higgidy Pies, said that "real investors" would not respond negatively to such a move.