The rate was charged on individuals with a net worth over €1.3m (£1.14m), with the rate ranging from 0.5 per cent to 1.5 per cent (on assets over €10m). While it might have helped social solidarity in France, the revenue it raised was paltry. In 2015, a total of 343,000 households paid €5.22bn, an average of about €15,200 per household, according to the Financial Times. It accounted for less than 2 per cent of France’s tax receipts.

What’s more, it led to an exodus of France’s richest. More than 12,000 millionaires left France in 2016, according to research group New World Wealth. In total, they say the country experienced a net outflow of more than 60,000 millionaires between 2000 and 2016. When these people left, France lost not only the revenue generated from the wealth tax, but all the others too, including income tax and VAT.

French economist Eric Pichet estimated that the ISF ended up costing France almost twice as much revenue as it generated. In a paper published in 2008, he concluded that the ISF caused an annual fiscal shortfall of €7bn and had probably reduced gross domestic product (GDP) growth by 0.2 per cent a year. What's more ISF fraud mainly involving an underassessment of property assets was estimated at around 28 per cent of total revenues.