Guernsey's government is carrying out a review into the so-called 1948 Agreement.
In 1948 Guernsey took control of many of Alderney's services after the island was largely destroyed during World War Two.
They say the islands have changed in the 70 years since the union was formed and with a deficit of £6.8 million incurred in 2017, it's time to look at whether this relationship is sustainable.
Accounts published by Guernsey's Policy and Resources Committee for 2017 show income from Alderney amounted to just over £11.1 million but the cost of services amounted to just under £18 million leaving a deficit of £6.8 million.
Alderney's government have decided not to comment on the review at this stage.