The deals, struck in Washington, will see the islands provide a rapid response service to American investigators looking for information on the various banks and companies based on Jersey and Guernsey.
Both islands had been under increasing diplomatic pressure from the US to be more open with information as it continues to crack down on tax havens internationally.
Despite being crown dependencies, neither island currently offers fast-track services for similar requests from British fraud officers, which has in the past hampered investigations.
Does Darwin's theory apply to taxation? Colin ponders...
The UK tax gap fell in 2014-15 to its lowest-ever level of 6.5%, revealed official statistics published today
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