The economic crisis following the COVID-19 pandemic has increased the debt levels of corporations and reduced the level of investments. Companies can use both equity and debt capital to finance investments. From a tax perspective, interest payments on debt are generally deductible from the corporate tax base, while costs related to equity are not. This debt-equity bias is a deep-rooted issue in today’s tax system and inhibits equity-financed investments. A recent ZEW policy brief shows that harmonisation at the European level is not suitable for solving the tax-induced distortion. Instead, the researchers recommend addressing the debt-equity bias on national level, e.g. by implementing a dual income tax.