March 1997 An investigation of the optimal boundary between public and private production. Huizinga and Nielsen investigate the optimal boundary between the public and private production sectors. They use a model in which government and private production coexist - in which a range of production activities can be carried out by either the government or the private sector. In effect, the government determines which activities to maintain within the public sector and which to privatize. In choosing the sectoral boundary, the government trades off the relative inefficiency of marginal government production against the private investment distortion created by tax policy. In an open economy, the private investment decision is distorted by a source-based income tax. In a closed economy, the private investment decision is distorted by either a private investment tax or a savings tax. Either tax produces a wedge between the gross return on investment and the net-of-tax return received by savers. Because of this tax wedge, the private cost of capital exceeds the shadow cost of public capital. Optimally, the government sector is shown to be too large in the sense that the government carries out some activities in which it has an efficiency disadvantage and the private sector has an efficiency advantage. And it invests more in those activities than the private sector would. Generally the size of the government sector is related positively to the investment tax wedge. The level of investment taxes - and thus the size of the state production sector - may be affected by tax competition in the international economy. As international capital becomes more mobile, there seems to be more scope for international (investment) tax competition. As a result of tax competition, perhaps, corporate income tax rates have been on a downward trend in European countries. In Europe, the general lowering of corporate income tax rates has coincided with a trend toward privatizing government activities. Huizinga and Nielsen focus on the relationship between capital income taxes and the size of the government production sector. Analogously, one could consider the relationship between labor income taxes and the size of the state sector. In that instance, the model predicts that a formerly state-owned enterprise, after privatization, reduces its payroll. Privatization also seems to lead to reduced employment levels. These results hold in both open economy and closed economy versions of the model. This paper - a product of the Finance and Private Sector Development Division, Policy Research Department - is part of a larger effort in the department to understand private sector development.