Provision of work covers various activities of an employee, the performance of which may lead to a result that is subject to copyright protection. This applies both to the performance of work under the classic employment relationship and the “academic employment contract,” containing elements characteristic for the performance of duties in the sphere of higher education and science. In both cases, the issues related to the creation and acquisition of economic copyrights to employee works are regulated by the provisions of the Act on copyright and related rights. In practice, however, a far-reaching (and incomprehensible) differentiation of tax-legal consequences can be observed in this respect, which becomes the source of numerous controversies in the context of law application. Problems are particularly visible in the area of calculating 50% (the so-called lump-sum) tax deductible costs. It should be emphasized at the same time that emerging interpretation difficulties result not only from the content of tax regulations. Their source is the provisions of the Law on higher education and science. The general (long-awaited) interpretation of the Minister of Finance sustained the legal dualism in the scope of the issue. The duality of the presented interpretation results from different treatment of employment contracts of academic teachers. It is pointed out that in order for the remuneration of academic teachers to be regarded as a royalty, a work must be created within the meaning of copyright law, but at the same time arguments are presented referring to non-statutory premises, which do not have normative overtones in the analysed case (e.g. prestige of the profession of academic teacher, which has features characteristic for liberal professions). The aim of the article is to outline the tax-legal consequences of the divergences and views persisting for a long time with regard to the treatment of employee’s works arising within the framework of employment relationship and to propose an appropriate interpretation direction supported by the Authors. For this purpose the dogmatic and historical-legal methods was used.