Several recent studies show that the elasticity of taxable income (ETI) is not a sufficient statistic for the welfare costs of taxation due to factors such as taxbase shifting. This paper provides an additional argument demonstrating the non-sufficiency of the ETI, namely tax deductions....

We develop and estimate a model of jointly optimal income taxes for different types of income. Compared to standard optimal tax formulas, optimal schedular income tax rates additionally depend on cross-elasticities between tax bases capturing fiscal externalities. We discuss two applications:...

This paper studies the tax treatment of couples. We develop two different approaches. One is tailored to the analysis of tax systems that stick to the principle that the tax base for couples is the sum of their incomes. One is tailored to the analysis of reforms toward individual taxation. We...