We explore the short- and long-run implications of tax competition between jurisdictions, where governments can only tax capital at source. We do this in the context of a neoclassical growth model under commitment and capital mobility. We provide a new theoretical perspective on the dynamic capital tax externalities that emerge in this model. Numerically, we show that the net capital tax externality is positive in the short run but converges to zero in the long run. We also find that noncooperative source-based capital taxes are initially positive and slowly decline toward zero.

We investigate optimal tax policy in a Romer-style endogenous growth model. We derive formulas for the optimal tax rates on capital, labour, and innovation on a balanced growth path. We compute the balanced growth path and the transition to it with optimal policy for a range of parameter values. We find that capital should be taxed in the short run, but be paid its marginal product in the long run. The returns to innovation and production labour, on the other hand, should always be lower than their marginal products. Whether the resulting taxes on innovative activity should be positive or negative depends on (a) the extent of government spending needs, (b) the importance of innovation externalities and (c) the market power of patent holders. The welfare gains from optimal policy are much larger than in a comparable exogenous growth model. 

We examine the role of fiscal policy in accounting for the remarkable rise of Ireland from one of Western Europe's poorest countries to one of its richest in just a few years. We focus on the importance of business tax reform and overall changes in fiscal policy, in conjunction with other factors, which we model as a residual rise in Total Factor Productivity (TFP). We conduct our analysis using a two-sector, small open economy model where production requires tangible and intangible capital services, and where inflows of capital are limited by a collateral constraint (disciplined to account for the GNP to GDP gap). We find that the much discussed reductions of business taxes played a significant, but secondary, role in the Irish miracle. However, tax reform and other changes strongly reinforce each other. We also find that Ireland's openness to capital movements was crucial: under the same driving forces, a closed economy would have experienced a significantly smaller rise in GDP.

In this paper we investigate tax competition in a neoclassical growth model where each country may use both residence- and source-based capital taxes. We show that both types of capital taxes are zero at any interior steady state, just as in a closed economy. For symmetric countries, and even for countries that differ only with respect to size and productivity, we prove analytically and verify numerically that the open-economy policies coincide exactly with the closed-economy policies in all time periods. For countries that are asymmetric in other dimensions, we find that source-based taxes are used to manipulate the intertemporal terms of trade in the short run. Either way, the fiscal externalities of source-based taxes vanish once residence-based taxes are allowed.

We study consumption risk sharing when individual income shocks are persistent and not publicly observable, and individuals can default on contracts at the price of financial autarky. We find that, in contrast to a model where the only friction is limited enforcement, our model has observable implications that are similar to those of an Aiyagari (1994) self-insurance model and therefore broadly consistent with empirical observations. However, some of the implied effects of changes in policy or the economic environment are noticeably different in our model compared to self-insurance.

In this paper, we study consumption risk sharing when individual income shocks are persistent and not publicly observable, and individuals can default on contracts at the price of financial autarky. We find that, in contrast to a model where the only friction is limited enforcement, our model has observable implications that are similar to those of an Aiyagari (1994) self-insurance model and therefore broadly consistent with empirical observations. However, some of the implied effects of changes in policy or the economic environment are noticeably different in our model compared to self-insurance.