New York Times, A Tiny Tax Could Do a World of Good, by Philippe Douste-Blazy:

As leaders of the world’s largest economies gather today in Pittsburgh for the Group of 20 meeting, people in the world’s poorest countries will likely look on with a mix of hope and trepidation, wondering whether their needs will figure in the deliberations at all. The G-20 nations could help both the poor and the global economy by fully financing lagging efforts to fight poverty and disease worldwide, and the best way to do this would be to impose a very small tax on the prosperous foreign exchange industry. …

Donor countries, including the wealthiest of the G-20, are providing only 0.3 percent of their combined income in development aid. Although the donor countries have made commitments to provide more money, they are not giving it fast enough to tackle runaway health problems, including the emergence of drug-resistant pathogens that threaten people across the globe.

The one untapped source that could easily provide the amount of money needed is the foreign currency market, which handles almost $800 trillion in trades annually, all of which is untaxed. A tiny levy of 0.005 percent on transactions involving the world’s most traded currencies — the dollar, the euro, the pound and the yen — would raise more than $33 billion annually for development, while not hurting the market or affecting the average international traveler.

The tax could be collected automatically by the computer system that handles foreign exchange transactions — so it would be easy to put into place, and impossible to evade. And because not all currencies would be taxed, only the countries whose currencies would be affected would need to consent. France already supports the idea, and Chancellor Angela Merkel of Germany has signaled her willingness to consider it.