The five largest economies in the European Union have agreed to share information on secret owners of businesses and trusts.
It is a concerted attempt to show their leaders are responding to public concern over the Panama Papers leak.
The UK, Germany, France, Italy and Spain have agreed to the data exchange.
However, the exchange is unlikely to placate critics who say that not enough has been done to crack down on global tax avoidance and tax evasion, often via offshore trusts and companies based in tax havens.
The agreement was announced at an unprecedented joint press conference of the finance ministers of the five EU countries at the IMF.