This thesis examines Sweden’s implementation of sanction provisions in cases of violations of the Supplementary Tax Act, with a particular focus on the reporting fee. Supplementary tax aims to ensure that multinational companies pay a minimum level of taxation regardless of where they operate. Sweden has implemented the supplementary tax provisions in accordance with the OECD model rules and the EU Minimum Tax Directive. To ensure accurate reporting and payment of the tax, various sanctions have been introduced, including the reporting fee, late submission penalties, and tax surcharges. 

A particular focus is placed on the reporting fee and its function as an administrative sanction. The thesis discusses whether the reporting fee is proportionally and effectively designed in accordance with the directive’s requirements and whether its placement within the Swedish Tax Procedures Act (SFL) is the most appropriate solution. One of the central questions examined is whether the reporting fee should have been regulated in the Supplementary Tax Act (TSL) instead of the Swedish Tax Procedures Act, to create a more tailored and legally secure regulation. Furthermore, the relationship between the reporting fee and tax offenses is analyzed, as well as how its design may affect the distinction between administrative sanctions and criminal penalties. The thesis also highlights the risk of double punishment and how the ne bis in idem principle could be impacted if the reporting fee were classified as a criminal sanction. 

In conclusion, the reporting fee plays a crucial role in the Swedish tax system by ensuring compliance with supplementary tax regulations. However, there remain challenges in its application, particularly regarding how the subjective assessment of the fee’s amount will function in practice. Additionally, questions arise concerning the extent to which the objectives of the Minimum Tax Directive’s sanction provisions will be fulfilled in legal practice, given that the legislator has chosen to incorporate the reporting fee into an existing regulatory framework, thereby limiting the possibility for a more tailored regulation of the supplementary tax's specific characteristics. Nevertheless, clearer guidance from legal practice could contribute to a more legally secure, predictable, and effective regulation of the reporting fee in the future.