And often the devil is in the detail. Whilst the residency test (no. of days in/out of country) is often the main factor in determining where a person is taxed often you can be caught in other ways. Examples could be having property in your "home" country, insurance policies, storage facilities etc. Each tax jurisdiction will have different ways of testing your residency and differing case law. Hence why you need to seek out expert advice from a specialist tax accountant who deals in the aviation sector.