The government says it's paying the UK around £3.3 million a year - but it's not sure what it's getting for its money.
A freedom of information request to the Cabinet Office asked for details about the Island's 30 year old agreement to make payments for defence.
In its response, the government said last year it paid £3,379,750 to the UK, up just under £80,000 on the year before.
But it added there's no list of what the payments fund - except they're in recognition of defence and other common services provided by the UK.
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