This contribution deals with matter of research and development and its practical problems in the Czech law system. The main aim of the paper is to confirm or disprove the hypothesis that effective legal regulation provides sufficient legal certainty for taxpayers to its investments to research and development and connected possibilities of tax deductible expenses. In the paper several legal (scientific) methods will be used such as comparison of science disciplines, implementation and analysis of premises and others. There is no integrated publication dealing with research and development in income tax law. For insight to problem of core matter judgements must be used.