The aim of this study is to investigate the effectiveness of research and development (R&D) tax incentives in generating additional business R&D expenditures in Turkey by applying propensity score matching (PSM) to correct any selection bias and to estimate the average treatment effect on the treated (ATT). Since the empirical literature lacks measurement of the effectiveness of these incentives in Turkey and partially touches upon global cases, this study contributes to fill this gap in the literature. For this purpose, the hypothesis that “R&D tax incentives increase business sector R&D intensity (the ratio of firm’s net R&D expenditures to total turnover)” is tested, and the effectiveness of R&D tax incentives is examined in the context of input additionality. The questions of whether R&D tax incentives are effective in increasing business sector R&D intensity and to what extent R&D tax incentives produce additional R&D intensity are answered. According to the results, R&D tax incentives have a positive effect on business sector R&D intensity. However, the additionality impact is limited since the R&D tax incentive multiplier is between 0 and 1.