This study explores empirically the effects of corporate income taxes on the incentive to invest in corporate social responsibility (CSR) activities. We estimate the relation between CSR ratings and firm‐specific corporate effective tax rates for a large sample of nonfinancial‐listed companies from 15 European countries during 2006–2016. By employing an instrumental variable approach, we find that average effective tax rates are negatively correlated with CSR ratings. Our findings are also consistent under additional tests and robustness checks. We, therefore, can provide suggestive evidence that corporate taxation discourages corporate socially responsible behaviour. At the same time, in a tax policy perspective, our analysis suggests how countries could encourage through the tax system the corporate provision of sustainable investments.