A leading centre for independent economic research has said the best evidence currently available suggests a 50p tax rate backed by Labourwill raise "little revenue" and make a "marginal contribution" to reducing the budget deficit.
Liberal Democrat Business Secretary Vince Cable has said Labour's proposed 50p income tax rate for those earning over £150,000 is an unnecessary, token gesture that will have negative effects.
Cable said his party were not interested in going down the 50p route, as it will fail to raise any meaningful revenue.
"We think it is unecessary, it's tokenism, it's not going to raise much, if any revenue. We do however believe there are a lot of unfairnesses in British society. It would be much fairer to have a tax on very high value property," said Cable
"The 50p rate is not a step forward...If we are serious about dealing with inequalities, we are much better dealing with unproductive wealth in the form of extreme property and the mansion tax on property over £2 million is the best way to do that," he added.
Ed Miliband answered questions for the first time this afternoon about his plans to re-introduce the 50p rate of income tax.
Politicians at both ends of the political spectrum need to be more honest about the true motivations behind their tax policies.
Ed Balls has said Labour would restore the 50p tax rate for those earning over £150,000 if the party wins the next election.