Jersey and Guernsey's governments have welcomed their inclusion on a "white list" of finance centres.
The status means the islands are among the most compliant centres in the world, reaching internationally agreed tax standards.
It follows the G20 summit of world leaders in London, where the regulation of finance centres was discussed.
The list was published by the Organisation for Economic Cooperation and Development (OECD).
It also features countries like the UK, USA, France and Germany.
A "black list" of the most secretive tax jurisdictions features Costa Rica, Malaysia, the Philippines and Uruguay.
There is also a "grey list" of 38 countries which have agreed to improve their tax standards but have not yet done so.
Lyndon Trott, Guernsey's chief minister, said the "white" rating was "a vindication of the tremendous effort we have put in over the last seven years".
"It's a relief, but not a surprise, we are here because it's where we belong," he added.
He said this would "put to bed the myth" that Guernsey is a tax haven.
Terry Le Sueur, Jersey's chief minister, said: "I am particularly pleased that the G20 leaders have recognised co-operative jurisdictions and have agreed to apply measures against those uncooperative jurisdictions, unlike Jersey, which have not committed to exchange tax information on request."
Guernsey and Jersey have signed a number of Tax Information Exchange Agreements (TIEAs) with other countries over the past few years to share information about tax issues and possible money laundering.
Jeffrey Owens, from the OECD, said: "The lead that these jurisdictions have taken in signing TIEAs, has played a big part in the developments in favour of greater transparency that we are now seeing around the globe."