SolvedVATPOSS03500 | Miscellaneous issues: Territory of the UK for VAT purposes
From HM Revenue & Customs · VAT Place of Supply of Services
The United Kingdom consists of Great Britain, Northern Ireland, and the waters within 12 nautical miles of their coastlines. It does not include the Isle of Man or the Channel Islands, which are treated as follows
the Isle of Man, although outside the UK, is treated as part of the UK for VAT purposes and VAT is chargeable under Manx law which generally parallels UK legislation
the Channel Islands are outside the UK for VAT purposes.