Extensive reforms to the country's taxation system were an integral part of Labour's plans for the modernisation of Britain and, despite its very narrow parliamentary majority, the new government immediately embarked on the most complex tax reform since the 1909 budget. This article considers the nature of that reform, concentrating on the new capital gains tax and the corporation tax, its two main elements, and its place in the modernisation project. It concludes that the implementation of the two new taxes represented a major achievement. In both cases, however, the government was forced to retreat from core objectives. It is argued that in large part this retreat was the product of inadequate prior consideration of how exactly tax fitted in with the party's wider modernisation project coupled with an excessive dependence on a single special adviser and a failure to secure a mandate for wide-ranging tax reform.