France's Constitutional Council overturned on Saturday a 75 percent upper tax rate on income above 1 million euros (816 thousand pounds) due to be introduced in 2013 by the seven-month-old Socialist government.
The decision, in response to a motion by opposition conservatives, is a huge blow to Socialist President Francois Hollande who had made the 75 percent rate his flagship tax measure as he sought to make the rich be seen to contribute more towards reducing the budget deficit.
While the planned upper tax band was mainly symbolic and would only have affected a few thousand people, it shocked foreign investors and infuriated high earners in France, prompting some such as actor Gerard Depardieu to flee abroad.
The government had estimated the 75 percent tax rate could raise around 300 million euros a year as it battles to bring down the public deficit to below a European Union ceiling of 3 percent next year in the face of stalled growth.
The Constitutional Council, which rules on whether laws are constitutional, said in a statement that the way the upper rate was set to be imposed was unfair in the way it would affect different households.
(Reporting by Emile Picy; Writing by Catherine Bremer; Editing by Robin Pomeroy)