This paper investigates the effect of tax incentives on R&D activities in Taiwanese manufacturing firms. Specifically, we assess the potential R&D-enhancing effect on recipients of R&D tax credits compared with their non-recipient counterparts. Moreover, the potential difference in the R&D-enhancing effect between high-tech and non-high-tech firms is also examined. Utilizing a firm-level panel dataset during 2001 and 2005, empirical results obtained by propensity score matching show that recipients of R&D tax credits appear on average to have 93.53% higher R&D expenditures and a 14.47% higher growth rate for R&D expenditures than non-recipients with similar characteristics. The R&D-enhancing effect of R&D tax credits is not found to be particularly relevant to high-tech or non-high-tech firms. We further employ a generalized method of moment (GMM) of the panel fixed model to control for the endogeneity of R&D tax credits and firm heterogeneity in determining R&D expenditure. Various estimates based on the entire sample and high-tech-firms are quite similar and there is a significantly R&D-enhancing effect of R&D tax credits. This result suggests that the R&D preferential policy has induced more R&D expenditure by firms in Taiwan. While the existence of the R&D-enhancing effect brought on by tax incentives is intuitive, the estimates can provide insightful implications for the R&D tax policy.