Local economists are renewing calls to merge critical public services across both bailiwicks.
IsleStat has published its proposal, called 'Vision CI', which sets out ideas for closer working.
Chris Brock is the company's principal consultant and says there are obvious areas to share services and cut costs:
"Functions such as health, education, law and order are the big spenders, yet two islands ,only 17 to 20 miles apart, have two separate administrations. There are dozens of best practice examples around the world where there is just one organisation covering a number of islands nearby."
He says that health alone costs more than £500m per year across the islands:
"It’s likely that health costs over the next 15 to 20 years could increase by up to 50% and that's a substantial figure when bearing in mind it’s nearly £0.5 billion to run the Channel Islands' health services. So if there is joint-working, there could be services in Jersey, some in Guernsey and reciprocal arrangements between the islands."
Guernsey's former chief minister deputy Gavin St Pier has previously called for joint-working between the two governments, the latest after the shock resignation of Jersey's chief executive in March.
But the islands are in two very different financial positions. Jersey reported its highest public sector income ever in 2022, the first time it had taken in more than £1 billion, while Guernsey's senior committee says a deficit of £100m a year is looming.
Guernsey's States will debate funding options, including GST, this week. It will be the third time the tax has been before the Assembly.
But Chris Brock says that the bailiwick's current fiscal situation is irrelevant:
"We're saying, what if there was one single health authority, or one single education body for the Channel Islands. How would it run, which services could be in each island? What front-line staff are necessary? And then to look at the costs, and if it saves money for both islands, or contains costs, that must be a good thing."
The report also recommends closer examination of a tunnel linking Guernsey and Jersey.