The pay of an air carrier employee who has regularly assigned duties on an aircraft in at least two states (for example, a pilot or flight attendant) is subject to income taxation by their state of residence and any state in which the employee earns more than 50% of the pay received. [49 U.S.C.S.

Commercial pilots typically pay income tax in the country where they are legally resident and, quite often, in the country where their airline is based (the "Place of Effective Management" or POEM). For international pilots, this can be complex due to the "Article 15(3)" provision found in many Double Tax Agreements (DTAs), which states that salary earned aboard an aircraft in international traffic is taxable in the state where the airline's management is located. However, many pilots are taxed based on the "Home Base" principle, particularly in the EU, where social security and certain taxes are tied to the airport where the pilot regularly starts and ends their duty periods. For example, a pilot living in Spain but flying for an Irish airline out of a base in Germany might have tax liabilities in all three countries, though DTAs generally prevent "double taxation." Pilots must also be wary of "days spent" rules; if they spend more than 183 days in a specific country, they may be deemed a tax resident there regardless of where they fly. Specialized aviation tax accountants are often required to navigate these multi-jurisdictional rules.