The council ruled that the tax was unfair because it would have applied unevenly to different households with the same combined income. A couple making a combined 1.5 million euros a year, for instance, would be exempt from the tax so long as both partners earned less than 1 million euros individually. If one partner earned more than 1 million euros, however, the couple would have been required to pay the 75 percent rate on their combined earnings of more than 1 million.

Mr. Hollande introduced the tax during his presidential campaign — a sharp break from his center-right rival, Nicolas Sarkozy, who had established a tax ceiling of 50 percent of earnings — to prove his leftist credentials in the face of a challenge from a candidate supported by the Communists, Jean-Luc Mélenchon.

Among the opposition on the right, politicians said the 75 percent rate was tantamount to theft, calling it “confiscatory” and insisting that it would drive investors and entrepreneurs out of the country. There have been reports and rumors of as many as 5,000 wealthy French citizens moving out of the country, though there are no official figures.

Most recently, in what has grown into a minor national scandal, it was revealed that the actor Gérard Depardieu would be taking up residence in Belgium, where there is no wealth tax and where the maximum income tax rate is 50 percent.

In France, without the 75 percent tax rate, the highest income tax rate will now be 45 percent. (With the invalidation of the 75 percent rate, French Twitter users have implored Mr. Depardieu to return to France, some facetiously, some not.) The 45 percent rate, which will apply to income above 150,000 euros, or about $198,000, is itself an increase from the previous top rate of 41 percent.