A Tobin tax is a small, uniform tax on every conversion of one currency into another, proposed by the American economist James Tobin to make short-term currency speculation less profitable. Because the tax is paid on each trade, it barely affects someone who changes money once for trade or long-term investment, but it adds up quickly for traders who move money in and out many times a year. Today the term is also used loosely for any financial transaction tax (FTT) on trades in shares, bonds or derivatives.
Tobin, a Yale professor who received the Nobel Memorial Prize in Economic Sciences in 1981, first presented the idea in lectures at Princeton in 1972 and published it in 1978 in "A Proposal for International Monetary Reform". He wrote after the collapse of the Bretton Woods system of fixed exchange rates, worried that a floating exchange rate world would be dominated by fast-moving capital that left national monetary policy little room. No country has adopted a pure Tobin tax on currency trades, but several tax share trading.
Tobin tax in plain terms
Imagine a toll booth on a bridge between two towns. A family that moves house crosses once and barely notices the fee. A courier who dashes back and forth dozens of times a day pays the toll every trip, so short, frequent journeys become much more expensive.
The Tobin tax applies that toll to money crossing between currencies. Tobin's hope was that it would calm sudden waves of buying and selling that can knock a currency off course, while leaving normal trade and long-term investment largely untouched. In his phrase, it would throw "sand in the wheels" of international money markets.
How the tax works
A trader who buys a currency and later sells it pays the tax twice. If the tax rate is and a position is opened and closed times a year, the yearly cost as a share of the amount traded is:
With a tax of 0.1% (), a company that converts money once a year for an investment pays , or 0.2%. A speculator who rolls a position over every week pays , or about 10.4% a year, enough to wipe out the small expected gains from most short-term bets, including many forms of carry trade.
The scale of the foreign exchange market explains the appeal to revenue seekers. The Bank for International Settlements reported average turnover of $9.6 trillion a day in April 2025, so even a tiny rate could, on paper, raise large sums, although trading volumes would fall in response.
From idea to policy
The proposal attracted little attention until the currency crises of the 1990s, including the 1992 to 1993 turmoil in Europe's exchange rate mechanism and the 1997 Asian crisis. Activist groups such as ATTAC, founded in France in 1998, campaigned for a Tobin tax to fund development, a use Tobin himself had not stressed and from which he distanced himself. The economist Paul Bernd Spahn proposed a two-tier version in 1995, with a very low normal rate and a much higher penalty rate during speculative attacks. Belgium passed a law for such a tax in 2004, conditional on other eurozone countries following, which they did not.
After the 2008 financial crisis, interest shifted to broader taxes on financial trading:
- European Union. The European Commission proposed an EU-wide financial transaction tax in 2011. When it failed to win unanimous support, 11 member states were authorized in 2013 to pursue it under "enhanced cooperation", but they had not agreed a common tax as of 2026.
- France and Italy. France has taxed purchases of shares in large French listed companies since 2012, and Italy introduced a similar tax in 2013 that also covers some derivatives.
- United Kingdom. Stamp duty and stamp duty reserve tax charge 0.5% on purchases of most UK shares, a much older form of transaction tax.
Arguments for and against
Supporters argue that a transaction tax reduces destabilizing speculation and hot money flows that can trigger a currency crisis, gives central banks more room to set monetary policy, and curbs the growth of high-frequency trading, which some regard as socially wasteful. It can also raise revenue from a lightly taxed financial sector, and some economists frame it as a Pigouvian tax on the costs of excessive trading.
Critics argue that the tax would reduce liquidity, widen the bid-ask spread and could even increase volatility, since much of the trading it deters comes from market makers who stabilize prices. Trading can move to untaxed centres unless every major financial hub joins: Sweden's tax on share trades, introduced in 1984, pushed much trading in Swedish shares to London and was abolished in 1991. Under tax incidence analysis, part of the cost may fall on ordinary savers through pension and investment funds. Others note that currency crises often have deeper causes, such as unsustainable pegs or fiscal problems, that a small tax cannot fix; capital controls are the more direct tool many emerging markets use.