The narrow streets around the Rue de Grenelle in Paris, a short stroll from the Boulevard St Germain, are dotted with familiar waystations of the internationally monied. There are smart restaurants, art galleries and designer clothes shops, among them Moschino and Dolce & Gabbana.

Above and between these places are townhouses and mansion apartments with grilled gates or with smoked-glass doors guarding the entrances – foyers hushed to the kind of silence that only serious money can buy. How serious the money is can be confirmed by a scan of the property pages online – in one case, almost €2m for a two-bedroom flat with three bathrooms.

It is in districts such as this, around Avenue Mozart and in Neuilly-sur-Seine, France's wealthiest postcode, that a cold wind has suddenly begun to blow, prompted by the announcement by François Hollande, France's Socialist president, that he intends to make good on his threat from February and soak les riches. That, we now know, will take the form of a two-year emergency tax of 75% on individuals earning more than €1.1m (£900,000) a year as part of his government's efforts to fill a €30bn hole in the public finances.

Even before Hollande delivered his announcement, he was pre-empted by the very public confirmation by France's wealthiest man, Bernard Arnault, head of the luxury goods firm LVMH, that he planned to apply to Belgium for dual nationality. The remarks were calculated to cause political impact, although Arnault later attempted to insist that he had no intention of ducking his French taxes.

It was an intervention by Arnault that prompted a tidal wave of condemnation – led by the leftwing French newspaper Libération, which published a picture of Arnault with a suitcase on its front page under the blunt headline: "Get lost – rich twat!"

While Arnault is now threatening to sue the paper for abuse, he has received little public sympathy. Fellow tycoon Edouard de Rothschild, a shareholder in the paper, gleefully backed its assault. France's political class has united across the ideological spectrum to condemn Arnault's manoeuvring – from the National Front's Marine Le Pen, who declared herself "shocked", to the far left's Jean-Luc Mélenchon, who said that the rich had no notion of "homeland except for money". Those occupying the political territory in between, including figures in both Hollande's Socialist party and the Gaullist UMP, have been no less scathing, accusing Arnault of behaviour tantamount to treachery in the middle of a national economic crisis.

If the debate seems strange to Anglo-Saxons, it is because French attitudes to wealth, taxation and the state are fundamentally different, though the issue of how much the wealthy should pay is not a new debate.

A year ago, at the dog-end of the presidency of Nicolas Sarkozy, a group of 17 prominent magnates issued a declaration in Le Nouvel Observateur asking to be taxed more (although none, it emerged last week, had quite in mind the rate Hollande is proposing). Indeed, when Le Monde revisited the signatories last week, it found that those who were willing to speak described the tax as "too onerous". "Morally it is legitimate," one said bitterly. "Economically and politically, it's stupid."

While it is a threat made by city types – to quit a city rather than pay more – that is more often uttered than acted on, what is clear is that some are leaving France. They are alarmed as much by the sense of uncertainty that in recent years has enveloped the French tax code as by the reality of the new tax, which most, it appears, will be able to avoid by deferring salaries above the new cutoff. The reality is that what both the tax and the reaction to Arnault speak of are complex and conflicted ideas about wealth and social responsibility in French society.

Driving to meet Steve Horton, a US tax accountant whose clients include bankers, entrepreneurs and high-flying American lawyers based in France, the taxi driver passes Fouquet's, the expensive restaurant where Sarkozy inadvisedly celebrated his own election victory, in company with pop star Johnny Hallyday, film star Jean Reno and high-flying businessmen, prompting the coining of the soubriquet President Bling Bling.

When asked about the restaurant, the driver recounts the story of Sarkozy's party again, where he snubbed the crowds of ordinary voters waiting to greet him elsewhere. I assume, because of this, the driver might be in favour of the new tax, but he is quick to condemn it as a "bad idea" that will hurt France economically. The rich, he thinks, should pay more tax, but not so much that they will be driven away.

Horton says he has already lost clients who might have been affected by the tax, including two American bankers, two lawyers and a French citizen based in the US who had recently moved his software company to France, but has gone back. He does a quick calculation on a piece of paper. He calculates that the combined lost taxes to the French exchequer – even before the advent of the supertax – amount to €14.5m a year for a handful of people.

"These were people who had been long-term residents," he says. "They had several homes here. They left before the announcement to London, New York and Moscow. They figured that they couldn't take the risk."

Horton remarks on a common theme that has emerged in the midst of the tax row – over his perception of very different attitudes to wealth among the French and his US clients. "If you go to a US cocktail party with the kind of people who are earning these sums, very quickly people will begin talking about their bonuses and share options. In France that is frowned on."

It is not only wealthy expats who have been spooked, according to Arnaud Jamin, a French tax lawyer for the company Fidal, who has his office in Neuilly-sur-Seine.

"There has been a lot of concern," he says of his French clients, adding that it was not only the new proposed tax. "In practice there are very few people in France who would pay the new tax. Maybe between 1,000 and 2,000. And some of those will benefit from loopholes. But it is the impression that it gives to those outside."

At the very heart of the issue, remarks Nicolas Tenzer – a political commentator and author, among other books, of The Elites and the End of French Democracy – is France's attitude to wealth, the state and social justice. "It is not a new phenomenon," he says. "Even in 1995 [the conservative] Jacques Chirac ran a campaign founded on the notion that social mobility was broken. All the polls suggest that people believe they live in a deeply divided society permeated with feelings of injustice and inequality."

It is a sense of "us and them" that was sharply underscored by Philippe Moreau Chevrolet, writing in Libération last week in a defence of its "Get lost" headline – a widespread suspicion that the country's elites are forever tempted to flee to more accommodating tax regimes, even though the "guillotines are not active".

"The suitcase of Bernard Arnault," he argued, "symbolises a frontier: between 'them' and 'us'. Them – the traitors who abandon the country in this period of trouble."

If few believe, however, that the new super-tax will do much to help Hollande balance the books, they admit that the issue conceals a wider fear – that it is a symbolic act to soften the blow for both cuts in services and spending and further increases in taxes for the wealthier middle classes.

Tenzer argues that this sense of division was exacerbated by the Sarkozy years with a president who became associated in people's minds with cutting taxes for his friends in the very wealthy elite – such as Arnault, who was best man at Sarkozy's wedding to the former model Carla Bruni.

It is in this context, Tenzer believes, that Hollande's new tax should be seen: as a symbolic political rebuke to the "bling bling" years, which he blames for the deep sense of anxiety afflicting French society, which Tenzer believes has corroded its social and fiscal contracts.

Tenzer describes the announcement, too, as a kind of socialist auto da fé on Hollande's part – like his declared hatred of the "rich" – to reassure his allies on the left at a time of very painful decisions. And despite the political outcry directed at Arnault, he suspects that the French are more ambiguous about the new tax than, perhaps, the front pages and politicians suggest. He adds that he has heard similar remarks to that of my taxi driver.

"There is a sense among even some ordinary Socialist supporters – and simple people, too, whom I have spoken to – that, yes, the system is globally unfair, but they are uncertain about what the 75% tax rate will really achieve," he says.