Governments around the world could raise more than $2 trillion (£1.5 trillion) by adopting Spain’s wealth tax on the super-rich, say activists calling for the money to be used to finance the climate transition.

As more countries consider raising taxes on the super-rich, campaign group Tax Justice Network said in a report that lessons learned from a “feather-light” tax on the 0.5 percent of richest households in Spain could help raise trillions of dollars worldwide each year.

The Spanish government under socialist Prime Minister Pedro Sánchez introduced a temporary “solidarity tax” on wealth at the end of 2022, which will be levied on individuals’ net assets exceeding €3 million (£2.6 million) in 2023 and 2024. It is estimated that it will apply to the richest 0.5 percent of households.

The Tax Justice Network said applying a similar tax to the wealthiest 0.5 percent of households worldwide, which range from 1.7 percent to 3.5 percent, would raise about $2.1 trillion. The study excluded some exemptions from the Spanish tax – including for shares in listed companies, intellectual and industrial property, and some high-value assets such as boats and aircraft.

It was said that up to 31 billion dollars would be raised annually from the UK.

The study comes as the G20, under the Brazilian presidency of left-wing politician Luiz Inácio Lula da Silva, discusses plans for a global minimum tax on the world’s 3,000 billionaires. France, Germany, Spain and South Africa have also signalled their support for the proposals.

However, it is likely to take years to reach an agreement and there may be resistance in several countries.

Alison Schultz, research fellow at the Tax Justice Network, said: “A minority of rich countries still appear to be reluctant to support a robust framework agreement on taxation – even though this is the best opportunity we have ever had and even though their own peoples are demanding that they act urgently.”

“This must change now – the climate cannot wait, and neither can the people of the world.”

Despite headlines warning that the super-rich may move elsewhere, the Tax Justice Network said previous reforms in some countries had not led to an exodus of the super-rich.

In Norway, Sweden and Denmark, only 0.01 percent of the richest households moved after the wealth tax reforms. According to a British study, the changes to the non-dom rules in 2017 led to a migration rate of just 0.02 percent.

In the UK, Rachel Reeves has previously ruled out the introduction of a new wealth tax. However, the Chancellor is abolishing non-dom status to raise more than £5 billion. She is also reportedly considering increasing taxes on capital gains, inheritances and pensions in the October 30 budget.