LONDON: A new report by tax researchers estimates the amount of black money deposited by a ‘global super-rich elite’ in offshore accounts is as much as 21 trillion dollars - equivalent of the combined GDP of the US and Japan.The report by Tax Justice Network released to The Observer is said to be the ‘most detailed estimates yet of the size of the offshore economy’.The Price of Offshore Revisited was written by James Henry, a former chief economist at the consultancy McKinsey and commissioned by the Tax Justice Network. He said $21 trillion is a conservative figure and the true scale could be $32tn.Henry used data from the Bank of International Settlements, International Monetary Fund, World Bank and national governments. His study deals only with financial wealth deposited in bank and investment accounts, and not other assets such as property and yachts.The report comes amid growing public and political concern about tax avoidance and evasion. Some authorities, including in Germany, have even paid for information on alleged tax evaders stolen from banks.The group that commissioned the report, Tax Justice Network, campaigns against tax havens.Henry said that the super-rich move money around the globe through an industrious bevy of professional enablers in private banking, legal, accounting and investment industries. “The lost tax revenues implied by our estimates is huge. It is large enough to make a significant difference to the finances of many countries.“From another angle, this study is really good news. The world has just located a huge pile of financial wealth that might be called upon to contribute to the solution of our most pressing global problems,” he said.The report highlights the impact on the balance sheets of 139 developing countries of money held in tax havens that is put beyond the reach of local tax authorities. The report suggests that for many developing countries the cumulative value of the capital that has flowed out of their economies since the 1970s would be more than enough to pay off their debts to the rest of the world.Henry estimates that since the 1970s, the richest citizens of these 139 countries had amassed $7.3 trillion to $9.3 trillion of ‘unrecorded offshore wealth’ by 2010 into secretive jurisdictions such as Switzerland and the Cayman Islands with the help of private banks. Private wealth held offshore represents ‘a huge black hole in the world economy’, Henry said.Other findings in the report include:* At the end of 2010, the 50 leading private banks alone collectively managed more than $12.1 trillion in cross-border invested assets for private clients* The three private banks handling the most assets offshore are UBS, Credit Suisse and Goldman Sachs* Less than 100,000 people worldwide own about $9.8 trillion of the wealth held offshore.According to Henry’s research, the top 10 private banks, which include UBS and Credit Suisse in Switzerland, as well as the US investment bank Goldman Sachs, managed more than 4 trillion pounds in 2010, a sharp rise from 1.5 trillion pounds five years earlier.According to Henry’s calculations, 6.3 trillion pounds of assets is owned by only 92,000 people, or 0.001 per cent of the world’s population - a tiny class of the mega-rich who have more in common with each other than those at the bottom of the income scale in their own societies.“These estimates reveal a staggering failure: inequality is much, much worse than official statistics show, but politicians are still relying on trickle-down to transfer wealth to poorer people,” said John Christensen of the Tax Justice Network.The report states that oil-rich states with an internationally mobile elite are especially prone to watching their wealth disappear into offshore bank accounts instead of being invested at home.“The problem here is that the assets of these countries are held by a small number of wealthy individuals while the debts are shouldered by the ordinary people of these countries through their governments,” the report says.