Aircraft are bound by the aviation authority to which they’re registered and must be operated in accordance with the rules and regulations of the countries’ aviation authorities through which they fly. For example an aircraft may be registered with the United States’ registry (N-reg), but operated in the United Kingdom. Each registry has its own set of rules and each have their pros and cons. Some owners pick the aircraft registry for tax reasons. Popular aircraft registries that are well known for being tax efficient include the Isle of Man Registry (M-reg), the Guernsey Registry (2-reg) and the Aruba Registry (P4-reg).