This project explores two ways in which the treatment of debt and equity could be equalised. Equity could be more generously treated, with an allowance for corporate equity (ACE). Or interest relief could be restricted, as under a comprehensive business income tax (CBIT). This project assesses the effects of each of these reforms if implemented in the EU. The results suggest that ACE would improve welfare if corporate tax rates were not increased to cover the cost of the narrower tax base. By contrast, under the same conditions CBIT would typically reduce welfare by exacerbating marginal investment distortions. However, if the tax rate were adjusted to make either reform revenue-neutral, the CBIT becomes more attractive and the ACE less attractive. European coordination of reforms mitigates tax spillovers within the EU and makes ACE more, and CBIT less, attractive for welfare. A combination of ACE and CBIT reforms can be designed to be revenue- neutral, and which would improve welfare through smaller financial distortions.