The taxation of aviation fuel has been restricted since the introduction of the Chicago Convention in 1944. Other international agreements have later fortified this prohibition. EU Member States are also obliged to refrain from taxing aviation fuel, as the Energy Taxation Directive comprises a prohibition against the taxation of aviation fuel referable to commercial flights. However, reducing air travelling is desirable as it is considered as one of the main contributors to climate change. In light of this, the restraint has been bypassed by some EU Member States through taxes on domestic air travel while leaving international flights (including those flights between Member States) untaxed. Some Member States have also chosen to apply taxes/fees to passengers in order to circumvent the prohibition. A range of taxes can therefore be found within the Member States, e.g. charter taxes, tourism taxes, taxation of commercial flights etc. Sweden recently introduced a new aviation tax with the purpose of disincentivising air travel and/or longer trips (Thailand being particularly popular with Swedes) for the benefit of other transportations, e.g. train. The tax is designed in accordance to the polluter pays principle as it applies a tax calculated in accordance to the final destination of the trip. Three categories of final destinations are applied in order to determine the fee, i.e. (1) 60 SEK (ca 6 Euro) per passenger travelling to a state within Europe. (2) 250 SEK (ca 25 Euro) per passenger travelling to a state outside of Europe. (3) 400 SEK (ca 40 Euro) per passenger travelling to a state not mentioned in the two appendixes listing states for previous two categories. The airlines are obliged to declare and pay the tax in order for the passengers to be directly burdened. The tax has, similar to many other environmental taxes, been widely debated both before and after its implementation. The public debate has primarily been focused on how it will impact the aviation industry and if the tax will have an actual positive impact on the environment. My contribution aims to describe the Swedish aviation tax and while doing so link it to EU state aid law as Member States. Distortions to the internal market are, as a general rule, not allowed and can be seen enforced through competition- and state aid law. State aid rules include taxes, as either a punitive tax or an incentive tax may distort competition between companies or industries. An aviation tax must therefore consider these rules in order for it to comply with EU law. A brief comparison to other aviation taxes within EU Member States will be done as the tax could be utilized as an example to other Member States. An aviation tax could also be discussed as a harmonized EU tax. Such a harmonized tax could contribute to fiscal revenues to the EU in addition to implementing a common environmental policy.