We examine the effects of taxes on Corporate Social Responsibility (CSR). Employing a tax reform in Korea that imposed a new tax on cash retention, we find that treated firms improved CSR performance after the tax reform was enacted. This result is driven by improvement in environmental and social performance. Moreover, the observed improvement is more pronounced in treated firms that face less severe financial constraints, are afforded fewer investment opportunities, feature large foreign ownership stakes, and employ stronger corporate governance mechanisms. The results suggest that tax increases lead to an increase in CSR investment and the magnitude of the increase depends on firm-level characteristics. As such, our results support the tax-strategic view of CSR in a country that has been a latecomer in incorporating CSR practices into business operations.