Till the IRS Do Us Part: (Optimal) Taxation of Households

This paper argues that a progressive tax system combined with individual taxation of married couples can generate more revenue than the current household-based U.S. system, especially when the extra revenues do not induce negative labor supply effects through increased government transfers. A progressive system that taxes individuals rather than couples jointly leads to larger labor force participation and higher average human capital, creates more “fiscal space”, Laffer curves shift up and social welfare potentially rises. In our model with one- and two-earner households, human capital and an extensive margin labor supply decision, the peak of the Laffer curve is 18 percentage points higher with an individual-based, progressive tax system than with the current U.S. tax system. The maximum revenue is attained with 100% more progressivity than the current system, and at an average tax rate of 42%. Progressive taxation, when imposed on individuals rather than households, lowers the average tax rate for individuals with modest potential income that are close to the participation margin. At the same time, it creates a positive income effect on the labor supply of these individuals by reducing the net income of their higher earning spouses and limiting their net earnings potential in the case of a high temporary labor productivity. Steady state social welfare is larger with individual taxation. The optimal progressivity is higher than the current U.S. status quo, and results in welfare gains of 0.8% in consumption-equivalent variation. Cohorts born during the transition also experience significant welfare gains from this reform.