Malkov, Egor2022-11-142022-11-142022-08https://hdl.handle.net/11299/243146University of Minnesota Ph.D. dissertation. 2022. Major: Economics. Advisor: Larry Jones. 1 computer file (PDF); 169 pages.This dissertation consists of three chapters which contribute to quantitative and theoretical understanding of inequality and associated public policies. The first essay studies how different should income taxation be across singles and couples. I answer this question using a general equilibrium overlapping generations model that incorporates single and married households, intensive and extensive margins of labor supply, human capital accumulation, and uninsurable idiosyncratic labor productivity risk. The degree of tax progressivity is allowed to vary with marital status. I parameterize the model to match the U.S. economy and find that couples should be taxed less progressively than singles. Relative to the actual U.S. tax system, the optimal reform reduces progressivity for couples and increases it for singles. The key determinants of optimal policy for couples relative to singles include the detrimental effects of joint taxation and progressivity on labor supply and human capital accumulation of married secondary earners, the degree of assortative mating, and within-household insurance through responses of spousal labor supply. I conclude that explicitly modeling couples and accounting for the extensive margin of labor supply and human capital accumulation is qualitatively and quantitatively important for the optimal policy design. In the second essay, I develop a framework for assessing the welfare effects of labor income tax changes on married couples. I build a static model of couples' labor supply that features both intensive and extensive margins and derive a tractable expression that delivers a transparent understanding of how labor supply responses, policy parameters, and income distribution affect the reform-induced welfare gains. Using this formula, I conduct a comparative welfare analysis of four tax reforms implemented in the United States over the last four decades, namely the Tax Reform Act of 1986, the Omnibus Budget Reconciliation Act of 1993, the Economic Growth and Tax Relief Reconciliation Act of 2001, and the Tax Cuts and Jobs Act of 2017. I find that these reforms created welfare gains ranging from -0.16% to 0.62% of aggregate labor income. A sizable part of the gains is generated by the labor force participation responses of women. Despite three reforms resulting in aggregate welfare gains, I show that each reform created winners and losers. Furthermore, I uncover two patterns in the relationship between welfare gains and couples' labor income. In particular, the reforms of 1986 and 2017 display a monotonically increasing relationship, while the other two reforms demonstrate a U-shaped pattern. Finally, I characterize the bias in welfare gains resulting from the assumption about a linear tax function. I consider a reform that changes tax progressivity and show that the linearization bias is given by the ratio between the tax progressivity parameter and the inverse elasticity of taxable income. Quantitatively, it means that linearization overestimates the welfare effects of the U.S. tax reforms by 3.6-18.1%. The third essay studies the policies that are aimed at mitigating COVID-19 transmission. Most economic papers that explore the effects of COVID-19 assume that recovered individuals have a fully protected immunity. In 2020, there was no definite answer to whether people who recover from COVID-19 could be reinfected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In the absence of a clear answer about the risk of reinfection, it is instructive to consider the possible scenarios. To study the epidemiological dynamics with the possibility of reinfection, I use a Susceptible-Exposed-Infectious-Resistant-Susceptible model with the time-varying transmission rate. I consider three different ways of modeling reinfection. The crucial feature of this study is that I explore both the difference between the reinfection and no-reinfection scenarios and how the mitigation measures affect this difference. The principal results are the following. First, the dynamics of the reinfection and no-reinfection scenarios are indistinguishable before the infection peak. Second, the mitigation measures delay not only the infection peak, but also the moment when the difference between the reinfection and no-reinfection scenarios becomes prominent. These results are robust to various modeling assumptions.enCouplesHeterogeneityInequalityPublic PolicyTaxationThesis or Dissertation