This report examines the European Commission's draft plans to introduce a Common Consolidated Corporate Tax Base (CCCTB) for EU group companies. It analyses the basic features of the draft proposal, as published in the draft CCCTB Directive of 16 March 2011 and the possible effects of these on the UK tax system. The report focuses on areas such as formulary apportionment, loss relief, intra-group transfers, reorganisations, the administration of the new system, taxation of inbound and outbound investment, and anti-abuse rules. Throughout this report, there is a comparison of the proposed rules with the UK provisions.