“We’re getting a lot of calls from high earners who are asking whether they should get out of France,” said Mr. Grandil, a partner at Altexis, which specializes in tax matters for corporations and the wealthy. “Even young, dynamic people pulling in 200,000 euros are wondering whether to remain in a country where making money is not considered a good thing.”

A chill is wafting over France’s business class as Mr. Hollande, the country’s first Socialist president since François Mitterrand in the 1980s, presses a manifesto of patriotism to “pay extra tax to get the country back on its feet again.” The 75 percent tax proposal, which Parliament plans to take up in September, is ostensibly aimed at bolstering French finances as Europe’s long-running debt crisis intensifies…

Many companies are studying contingency plans to move high-paid executives outside of France, according to consultants, lawyers, accountants and real estate agents — who are highly protective of their clients and decline to identify them by name. They say some executives and wealthy people have already packed up for destinations like Britain, Belgium, Switzerland and the United States, taking their taxable income with them.