The tax would be paid by any UK resident (including "non-doms" and recent emigrants) with personal wealth above a set threshold. They would be taxed on all assets, such as main homes, pension pots, business and financial wealth, but not on any debts such as mortgages, and pay over five-year instalments.

Debate has been brewing about how the UK is going to pay down debt that is running at more than 100 per cent GDP as the government has thrown the fiscal kitchen sink at the crisis. The country’s wealthiest have been obvious first targets for clawing back funds, not least because they have weathered the crisis better than most and have been the main beneficiaries of massive central bank quantitative easing, which has helped drive up asset prices.

The report’s authors, made up of academics from the London School of Economics and the University of Warwick, with input from barristers advising high net worth clients, called the solution “fair, efficient, and difficult to avoid.” While it is not binding, it might give valuable ammunition for Chancellor of the Exchequer Rishi Sunak, who needs to repair ravaged public finances.

On tax fairness, the research said that those with the most wealth have the ‘broadest shoulders’ to afford an additional contribution to the State in times of crisis. On efficiency, unlike taxes on work or spending, a one-off wealth tax would not discourage economic activity, they said. (Also administrative costs would be small as a proportion of revenue raised.) On payment, a one-off wealth tax is not going to be evaded by leaving the country or moving money offshore. “If well designed, it would be very difficult to avoid the tax legally,” the report said.

“We’re often told that the only way to raise serious tax revenue is from income tax, national insurance contributions, or VAT. This simply isn’t the case, so it is a political choice where to get the money from, if and when there are tax rises,” assistant professor at the University of Warwick, and report co-author Dr Arun Advani, said, defending the proposal.

France, Germany and Japan imposed similar one-off tax measures to recoup costs following the Second World War, and Ireland used a wealth tax to reboot its economy after the Global Financial Crisis. A number of countries down the years have had wealth taxes, such as Sweden, although in some cases they were discontinued.

Wealth taxes have been mentioned before the pandemic as ways to curb the increased inequality that has arguably been driven by central bank QE and aspects of globalisation. Half a decade ago, French academic Thomas Piketty provoked controversy by calling for higher taxes on the "the rich", such as on their capital, prompting criticism that taxes on capital have been counterproductive in the past, and that these are also assaults on wealth that has already been taxed in its creation.

Critics say that taxing wealth in reality means taxing investments, and will indirectly hit the activity such investments drive. Even so, that wealth taxes have been on the agenda highlights how the question of "wealth justification" remains a live issue.

Calculations
Although yesterday's report, funded by the Economic and Social Research Council, didn’t suggest when such a tax could start or recommend specific rates or thresholds, it did offer up different household calculations.

Example 1: At a threshold of £1 million per household (assuming two individuals with £500,000 each) and a rate of 1 per cent a year on wealth above the threshold, a one-off wealth tax would raise £260 billion over five years after administration costs. This is equivalent to raising VAT by 6p or the basic rate of income tax by 9p for the same period.

Example 2: At a threshold of £4 million per household (assuming two individuals with £2 million each) and a rate of 1 per cent a year on wealth above the threshold, a one-off wealth tax would raise £80 billion over five years after administration costs.

“People sometimes say the super-rich won’t pay. My experience is they are happy to pay, as long as the tax is simple to operate, affordable and they don’t feel they aren’t being singled out with penal rates,” said Emma Chamberlain, another co-author and barrister at 's tax expert Rachael Griffin sees problems arising from the practical implementation of such a tax. "The proposals recommend a levy on anyone with assets over £500,000, or £1 million for a couple. That means that for a huge number of moderately affluent people, the valuation on their home may or may not mean they’re affected. Getting so many properties valued fairly and accurately would be a huge challenge.

“Similarly, how would you value an insurance or pension policy which may have cost a significant sum and pays a sizeable amount, but which isn’t sat as a capital sum in someone’s account? And where somebody has substantial wealth in a business it would be hugely problematic to value fairly in many cases, and could cause other complications."

For Griffin, all these complications will rally opponents and send the message to inward investors that the UK is happy to ‘soak the rich’. But the proposal may pave the way for increasing taxes in the existing system, she said. "Were the Chancellor inclined to raise more revenue from existing taxes on capital, such as CGT and IHT, he now has some political cover since he can point to the alternative being a £260 billion raid on personal wealth.”

The commission consulted with economists from Institute for Fiscal Studies, Resolution Foundation, Institute for Government and the OECD to reach its findings. It also took evidence from tax practitioners and policymakers, including the former head of HMRC.

The report launched with a website where the public can model their own revenue-raising options, and see how much they would pay under different options.