PARIS — The call to Vincent Grandil’s Paris law firm began like many others that have rolled in recently. On the line was the well-paid chief executive of one of France’s most profitable companies, and he was feeling nervous.

President François Hollande is vowing to impose a 75 percent tax on the portion of anyone’s income above a million euros ($1.24 million) a year. “Should I be preparing to leave the country?” the executive asked Mr. Grandil.

The lawyer’s counsel: Wait and see. For now, at least.

“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.