The Institute of Directors (IoD) said Labour must "drop its practice of knee-jerk reversion to the old socialist nostrums" if the party wants to be taken seriously by business.
Director general Simon Walker said: "The 50p tax rate - actually 52p, because the last Labour government manipulated national insurance contributions - greatly damaged Britain's claim to being seen as a low-tax economy and actually drove down total tax receipts.
"It was, and remains, an envy-driven political gesture designed solely to drive a wedge between voters."
He added, "It will significantly damage Labour's credibility with the business community."
According to an Institute of Directors poll, the proportion of business leaders who expect 2013 to improve on the previous year exceeds those with a pessimistic outlook by more than a third - a direct reversal from the start of last year.
The numbers foreseeing a high risk of a triple dip recession has fallen from approximately one in three to one in six.
Views on the probability of a return to recession has fallen too.
There is a growing sense of economic optimism for the year ahead compared to 12 months ago, a poll of business directors has suggested.
A survey of 1,369 members of the Institute of Directors (IoD) found that business leaders are starting 2013 with a better outlook on the coming year than at the beginning of 2012.
2012 was a tough year, but business leaders expect 2013 to be much better. The risk of a return to recession and a triple dip has not gone away, but it is receding fast, and expectations of growth are rising.
George Osborne's approval ratings have suffered, but he retains business support overall. The deficit reduction programme in particular has overwhelming backing from UK directors - the Government absolutely must not waver from the course.
– Graeme Leach, Institute of Directors Chief Economist
Month after month the country's businesses have been telling the Government it is not doing enough to lift our economy out of this double-dip recession created in Downing Street. But out-of-touch and ineffective ministers refuse to listen, which is why they are losing the confidence of business. The IoD is right to point out that 'low confidence leads to delayed decisions'. In order to have the confidence to invest, business needs far more certainty from Government, but what they have got on policy - from aviation to renewable energy - is indecision.
The government says it has set out a comprehensive strategy which aims to achieve strong, sustainable and balanced growth. In a statement it said:
"Savings to business from cuts in regulation have outweighed the costs of new domestic regulation by more than £850m and reform of labour laws has already led to an increase in the qualification period for unfair dismissal and reform of employment tribunals.
Business is battening down the hatches in the expectation that the recession will continue for the rest of the year. That is bad news for the economy at large, because decisions to invest money or take on more staff are being postponed until things look up. Low confidence leads to delayed decisions, and delayed decisions further undermine economic confidence - it's a vicious cycle. At the same time, the Government's reform agenda is pointing in broadly the right direction, but the overwhelming opinion of our members is that they are doing too little, too slowly.
– Graeme Leach, chief economist at the Institute of Directors