50p tax claims: Charlie Mullins and Richard Murphy
1 March 2012 Last updated at 13:58 GMT
Charlie Mullins, Pimlico Plumbers founder, said the 50p tax rate was stopping firms from expanding and had seen the government lose £500m in the amount of tax collected.
He was one of 500 business leaders to write to the Daily Telegraph calling for the top rate of tax to be cut in the Budget on 21 March.
But Richard Murphy, chartered accountant and founder of Tax Research UK, claimed it could raise £5bn with 300,000 people earning more than £47bn.