Tax systems and public borrowing limits in a fiscal union

This paper compares the implications of tax system and public borrowing limit asymmetries for the welfare cost of business cycles and interregional consumption risk sharing in a two-region fiscal union. We identify the welfare-improving and risk-sharing-improving designs of the regional tax systems and borrowing limits. We find that the choice of public borrowing limits is more consequential than is the choice of a tax regime for union welfare. It also serves as an argument for the harmonization of fiscal policies adopted in the fiscal union, as it would internalize fiscal externalities and improve consumption risk-sharing across the union regions. The key parameter determining the merits of alternative regional tax systems and possible limits to public borrowing in the fiscal union is the productivity of public good. Other aspects of the economy, such as the type of technology process, or the nature of the productivity shock do not affect the union public finance system design significantly. Extensive simulations suggest that if the productivity of public capital lies within the range of plausible empirical estimates, allowing both regions to have flexible borrowing limits and to choose whatever tax system they prefer will reduce the overall welfare costs of business fluctuations. However, for very low productivity of public capital, the welfare-improving regional public finance reforms that would prohibit public borrowing and tax labor income can produce limited benefits.