Thesis: The four research articles composing this PhD dissertation study the sharing of fiscal resources used to provide common public goods or transfers to contribute to macroeconomic stabilization. In the first chapter, we consider an optimal centralization problem with jurisdictions that have heterogeneous preferences for public goods and tax a mobile base to finance them. We adopt a theoretical model with a federal structure and a continuum of public goods to draw several normative conclusions from the study of the optimal degree of centralization. The contribution of this second chapter is to consider a tax competition model where public goods potentially exhibit cross-border spillovers. We show that full cooperation can be attained if spillovers in public good provision are high enough to remove the incentives to remain a low-tax non-cooperative player. In the third chapter, we build a DSGE model of the euro area (with a core and a periphery) with nominal, labor and financial rigidities. A baseline model where policies are only national, as it is the case now, is set as the reference for calibration which reproduces key empirical observations for the euro area. Then, we implement a common unemployment insurance and study its stabilization properties. The fourth chapter focuses on how a fiscal capacity targeting directly households can improve stabilization at the zero lower bound.