In the modern economy the budget is not only a simple document that contains the state revenue and expenditure over a period of twelve months, but it is a financial plan at the macroeconomic level. The budget process is both technical and political. It is indisputable that it can not be separated from the state and the governing, however, this article analyzes the technical side of the budget elaboration, focusing on the methods for sizing the public budget income and expenditures. Given the increasing role of the state budget, modern management techniques are required, because planning a realistic state budget is a first step towards a good governance of the country.