The Lib Dems are opposed to the non-dom rule, and are set to confirm commitments to cut the basic rate of income tax by four pence in the pound, paid for by a crackdown on capital gains tax paid by private equity chiefs and non-doms.

Shadow Chancellor Vincent Cable also plans to concentrate on elaborating proposals to ‘radically simplify the tax code’, removing hundreds of pages of regulations.

The non-dom rule costs the UK up to £4.3bn a year, according to calculations for the TUC by tax campaigner Richard Murphy. TUC general secretary Brendan Barber said: ‘A significant group of super-rich think that tax is for the little people.’