This article describes the changes that have taken place in the work of the Budget Office of the central government as a consequence of the transition from the traditional budget process, often referred to as “incremental budgeting”, to top-down budgeting. This transition has taken place in most OECD countries in the course of the last three decades and has generally led to the end of the century-old trend of growth of the public sector relative to GDP. As a consequence of this transition the role of the budget office has shifted from operational expenditure control to supervision on the maintenance of the medium term expenditure framework. In general this has led to a more co-operative relationship between the Budget Office and the financial divisions of the line ministries. This article is based on case studies in three countries, namely the United Kingdom, the Netherlands and Slovenia and highlights the differences in their budgeting procedures and the extent to which the transition to top-down budgeting has been implemented.