The purpose of this thesis was to analyse if the six month rule in chapter 3 § 9 part 1 in IL is compatible with EU law regarding the free movement of employees and in case of discrimination whether the rule can be justified. First of all the retroactive salary for an unlimited taxpayer and during the period of income earning a limited taxpayer who later became unlimited taxpayer will be analyzed in order to determine if they are considered to be in a comparable situation. An unlimited taxpayer is subject to taxation in Sweden for all of his incomes regardless their origin. However there is an exception according to six month rule, which implies that physical persons who stay abroad due to their minimum six months employment are in Sweden free from their incomes earned abroad if they are taxed in the country of employment. Tax exemption is applicable even if the payment from an employee working abroad is made retroactively.

Article 18 EUFF states a general prohibition of discrimination on the grounds of nationality. In the area of tax legislation it happens not very often that physical persons become an object of direct discrimination. The direct discrimination as well as all form of indirect discrimination is included in prohibition of discrimination. The comparable situations where different rules are applied result in discrimination. The situations given in the thesis are considered to be comparable but the six months rule has only resulted in tax exemption in one of the situations, which implies that discrimination took place. The discrimination depended on other criteria than nationality but the result was the same as the discrimination on the grounds of nationality. Depending on some circumstances the indirect discrimination can be justifiable with help of the "rule of reason"-test. Although the six months rule is incompatible with the EU law it can be justified considering the cohesion of the tax system.