How do corporate tax bases change when corporate tax rates change? With implications for the tax rate elasticity of corporate tax revenues

We construct a new database of extensive margin changes to multiple aspects of corporate tax bases for OECD countries between 1980 and 2004. We use our data to systematically document the tendency of countries to implement policies that both lower the corporate tax rate and broaden the corporate tax base. This correlation informs our interpretation of previous estimates of the relationship between corporate tax rates and corporate tax revenues, which typically do not include comprehensive measures of the corporate tax base definition. We then re-examine the relationship between corporate tax rates and corporate tax revenues. We find that accounting for unobserved heterogeneity attenuates the relationship between corporate tax rates and corporate tax revenues, and increases the implied revenue-maximizing tax rate. Controlling for our new tax base measures does not substantively impact the magnitude of this relationship.