The focus of this paper is on effects from tax incentives for research and development inputs (R&D) and corporate income tax on business R&D and patenting behaviour. First, we provide a theoretical discussion of tax planning with R&D and intellectual property (IP) ownership. Further, we employ firm-specific micro-data on patent applications of European corporations at the European Patent Office to test reactions on changes in R&D tax incentives and corporate tax burden. We find a positive impact of R&D tax incentives and a negative impact of the statutory corporate income tax rate on patenting. R&D incentives rather influence the tendency to invest in R&D, whereas the tax burden rather influences the scale of R&D investment and the count of patent applications.