The geography of tax avoidance and evasion – far-flung yet interwoven – means reform is, in isolation, ineffective. The structures merely move. Gabriel Zucman, an academic from the London School of Economics and the author of The Hidden Wealth Of Nations: The Scourge Of Tax Havens, estimates that $7.6 trillion (8 percent of individual financial wealth) is held in tax havens. That means approximately $190 billion is lost in tax revenue.