In his Budget speech, Osborne said: "No chancellor can justify a tax rate that damages the economy and raises next to nothing."
He said through taxing "the rich" the revenue would receive five times as much after the reduction.
Richard Manion, national tax director at Smith & Williamson, said: "This will change company behavior - it will change how employers award their bonuses and dividends - it's an emotional and not economic issue."
But he added: "Entrepreneurs will feel better about recruitment and they will make less effort to avoid paying tax."
Carol Dempsey, a partner at PwC, added: "The 45p tax rate should raise more revenue. I think among employers there was a bad feeling about the overall tax system attracting top talent into the UK and I think there is economic work to be done, to decide what is the optimal rate of tax to attract the right people, would be."