Britain's top earners are set to receive a tax cut of more than £100,000-a-year, Labour leader Ed Miliband will claim.
The party said it would be publishing new figures showing that the 8,000 people earning over £1 million stand to benefit by an average of £107,500 as a result of Chancellor George Osborne's tax changes.
Labour has previously said that earners on more than £1 million stood to gain £40,000 a year as from Mr Osborne's decision in the Budget to cut the top rate of tax from 50p to 45p.
But it has now calculated that the actual figure is even higher.
The claim comes as Mr Miliband and shadow chancellor Ed Balls were set to hold a question and answer session with workers at a sheet metal factory in Stevenage ahead of next week's autumn statement on the economy.
Mr Miliband is expected to tell them that they were paying the price for the Government's decision to stand up for the "wrong people".
"David Cameron and George Osborne believe the only way to persuade millionaires to make work harder is to give them more money. But they also seem to believe that the only way to make you work harder is to take money away," he is expected to say.
"Cut your tax credits, squeeze your living standards, get rid of some of the services on which you rely, and put up VAT. That's where the money is coming from for the millionaires' tax cut."