Jersey has signed tax information exchange agreements with Brazil and Latvia, the States says.
The agreements were signed by external relations assistant chief minister Sir Philip Bailhache at the countries' embassies in London.
It will allow the countries to ask for tax information Jersey has on their citizens.
Sir Philip said "great importance" was attached to such agreements as they showed commitment to tax transparency.
Speaking about the Latvian agreement, he said: "While Jersey is not a part of the European Union, we are part of Europe and we have long pursued a good neighbour policy towards the member states of the EU."
He added that the Brazilian agreement would help maintain good relationships with the G20, of which Brazil was a member.
Jersey has now signed tax agreements with 17 G20 countries.