Research Interests

Primary: Macroeconomics, Computational Economics
Secondary: Public Finance

Published Papers

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Determining the Motives for a Positive Optimal Tax on Capital
(Journal of Economic Dynamics and Control, 2013, 37 (1), 265-295)

Previous literature demonstrates that in a computational life cycle model the optimal tax on capital is positive and large. Given the computational complexities of these overlapping generations models it is helpful to determine the relative importance of the economic factors driving this result. I highlight the effect of changing two common assumptions in a benchmark model that generates a large optimal tax on capital similar to the model in Conesa et al. (2009). First, the utility function is altered such that it implies an agent's Frisch labor supply elasticity is constant, as opposed to increasing, over his lifetime. Second, the government is allowed to tax accidental bequests at a separate rate from ordinary capital income. The main finding of this paper is that these two changes cause the optimal tax on capital to drop by almost half. Furthermore, I find that the welfare costs of adopting the high optimal tax on capital from the benchmark model in the model with the altered assumptions, which calls for a lower tax on capital, are equivalent to 0.35 percent of total lifetime consumption. Quantifying the effect of these assumptions in the benchmark model is important because the first has limited empirical evidence and the second, although included for tractability, confounds a motive for taxing capital with a motive for taxing accidental bequests.

Reconciling Micro and Macro Estimates of the Frisch Labor Supply Elasticity
(Economic Inquiry, 2016, 54 (1), 100-120)

This paper explores the large gap between the microeconometric estimates of the Frisch labor supply elasticity (0-.5) and the values used by macroeconomists to calibrate general equilibrium models (2-4). These two ranges identify two fundamentally different notions, the micro and macro Frisch elasticity, respectively. Due to the different definitions, there are two restrictions in the micro Frisch elasticity that are relaxed in the macro Frisch elasticity. First, the micro Frisch elasticity focuses only on prime-aged married males who are the head of their household, while the macro Frisch elasticity represents the whole population. Second, the micro Frisch elasticity only incorporates intensive margin fluctuations in hours, while the macro Frisch elasticity includes both intensive and extensive margin fluctuations. This paper finds that relaxing these two restrictions causes estimates of the Frisch elasticity to increase from 0.2 to between 2.9 and 3.1, indicating that these two restrictions can explain the gap between the microeconometric estimates and the calibration values. However, this paper demonstrates that these estimates of the macro Frisch elasticity are sensitive to the estimation procedure and also the exclusion of older individuals, implying that calibration values used for macroeconomic models should be selected carefully.

The Effect of Endogenous Human Capital Accumulation on Optimal Taxation
(Review of Economic Dynamics, 2016, 46-71)

This paper considers the impact of learning-by-doing on optimal tax policy in a general equilibrium heterogenous agent life-cycle model. Analytically, it identifies two main channels by which learning-by-doing alters the optimal tax policy. First, learning-by-doing creates a motive for the government to use age-dependent labor income taxes. If the government cannot condition taxes on age, then a capital tax or progressive/regressive labor income tax can be used in order to mimic age-dependent taxes. Second, a progressive/regressive labor income tax is potentially more distortionary in a model with learning-by-doing since the distortion is propagated through the additional intertemporal link between current labor and future human capital. Quantitatively, I find that both of these channels are important for the optimal tax policy. Adding learning-by-doing leads to a notably flatter optimal labor income tax due to the second channel. Moreover, including learning-by-doing causes an increase in the optimal capital tax due to the first channel. I find that when solving for the optimal tax policy in the learning-by-doing model, the welfare consequences of not accounting for endogenous human capital accumulation are equivalent to around one percent of expected lifetime consumption, a majority of which are due to adopting too progressive of a tax policy.

Under Review

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How Well Did Social Security Mitigate the Effects of the Great Recession?
with Kamila Sommer (Revision Requested by International Economic Review)

This paper quantifies the welfare implications of the U.S. Social Security program during the Great Recession in a computational life cycle model. We find that Social Security reduces the average welfare losses for agents alive at the time of the Great Recession by the equivalent of 1.4% of expected future lifetime consumption. Zooming in on the effect of the program for particular groups, we find that Social Security is particularly effective at providing insurance for agents who are poorer, less productive, or older at the time of the shock, and therefore mitigates substantially more of these agents' welfare losses. In addition, despite the potentially adverse effects of the program, we do not find any specific age, income, wealth or ability group for which Social Security more than slightly exacerbates the welfare consequences of the Great Recession. Despite Social Security's effectiveness at mitigating the welfare effects of the Great Recession, consistent with previous studies, we find that it substantially reduces average long run welfare in the steady state. Therefore, we quantify the tradeoff between reducing average long run welfare in the steady state and mitigating welfare losses during business cycle episodes in a smaller, means-tested program, in the spirit of Supplemental Security Income. We find that this smaller more progressive program can provide a significant fraction of the mitigating effect, while causing much less reduction in long run average welfare.

A Historical Welfare Analysis of Social Security: Who Did the Program Benefit?
with Kamila Sommer (Second Revision Requested by Quantitative Economics)

This paper builds a computational life cycle model and simulates the Great Depression in order to assess the historical welfare implications of implementing Social Security during this business cycle episode. A well established result in the literature is that when comparing steady states with and without Social Security in a standard life cycle model, steady state welfare tends to be lower with Social Security. Consistent with these previous results, this paper determines that on average in the steady state the original Social Security program lowers welfare by the equivalent of 2.5% of expected lifetime consumption. Moreover, the likelihood that this Social Security program causes a decrease in an agent's welfare in the steady state is 92%. However, this paper finds that the welfare effects of implementing Social Security for agents in the economy at the time the program is adopted is very different than these steady state welfare effects. In particular these living agents experience an increase in their lifetime welfare due to the implementation of Social Security that is equivalent to 5.9% of their expected future lifetime consumption. Moreover, the paper finds that the likelihood that these living agents experience an increase in their lifetime welfare due to the adoption of the program is 83%. The divergence in the steady state and transitional welfare effects is primarily driven by a slower adoption of payroll taxes and a quicker adoption of benefit payments. This divergence could be one explanation for why a program that decreases steady state welfare was originally implemented.

The Distributional Effects of a Carbon Tax on Current and Future Generations
with Stephie Fried and Kevin Novan (Conditionally Accepted at Review of Economic Dynamics)

This paper uses a life cycle model to compare how different approaches for recycling carbon tax revenue affect the welfare of agents born in the future steady state versus agents alive when the policy is adopted. Our results demonstrate that the welfare consequences of a given policy vary substantially across these two groups. For agents born into the future steady state, the expected non-environmental welfare costs are minimized when carbon tax revenue is used to reduce an existing distortionary tax. In contrast, among the agents alive when the policy is adopted, recycling revenue through uniform, lump-sum rebates results in the largest welfare increase across the policies we examine. Moreover, we find that the regressivity or progressivity of a policy also differs within the living population versus the future steady state population. Overall, our results illustrate that estimates of the non-environmental welfare costs of carbon tax policies that are based on the long-run outcomes miss-represent the near-term consequences. Given the potential importance of these near-term effects on the political feasibility of a policy, our findings indicate that, when designing a carbon tax, policy makers must pay careful attention to not only the long-run outcomes, but also to the transitional welfare effects of the policy.

Fiscal Policy and Aggregate Demand in the US Before, During and Following the Great Recession
with David Cashin, Jamie Lenney, Byron Lutz (Revision Requested at International Tax and Public Finance)

We examine the effect of federal and subnational fiscal policy on aggregate demand in the U.S. by introducing the fiscal effect (FE) measure. FE can be decomposed into three components. Discretionary FE quantifies the effect of discretionary or legislated policy changes on aggregate demand. Cyclical FE captures the effect of the automatic stabilizers—changes in government taxes and spending arising from the business cycle. Residual FE measures the effect of all changes in government revenues and outlays which cannot be categorized as either discretionary or cyclical; for example, it captures the effect of the secular increase in entitlement program spending due to the aging of the population. We use FE to examine the contribution of fiscal policy to growth in real GDP over the course of the Great Recession and current expansion. We compare this contribution to the contributions to growth in aggregate demand made by fiscal policy over past business cycles. In doing so, we highlight that the relatively strong support of government policy to GDP growth during the Great Recession was followed by a historically weak contribution over the course of the current expansion.

Taxing Capital? The Importance of How Human Capital is Accumulated
(New Version)

This paper explores both analytically and quantitatively how the optimal capital tax changes when human capital is accumulated in three different cases: (i) exogenously, (ii) endogenously through learning-by-doing (LBD), (iii) and endogenously through learning-or-doing (LOD). While Peterman 2016a demonstrates that the optimal tax on capital increases when human capital is accumulated through LBD as opposed to exogenously, it is still unknown whether this result is robust to other forms of endogenous human capital accumulation. Analytically this paper demonstrates in a simple two period model that including either LBD or LOD create novel motives for the government to use age-dependent labor income taxes. If the government cannot condition taxes on age, then a capital tax can be optimal in order to mimic age-dependent taxes. However, the channel by which these two forms of endogenous human capital affect the optimal capital tax are quite different. LBD causes a change in the optimal tax because young agents supply labor relatively less elastically. In contrast, LOD changes the optimal tax because it causes young agents to supply labor relatively more elastically and provides the ability for agents to save both via training and ordinary capital. Turning to a quantitative model, these different channels lead to numerically different effects on the optimal capital tax from including either LBD or LOD. Including human capital accumulation with LOD, as opposed to exogenously, causes the optimal capital tax to increase by between 0.7 and 3.7 percentage points. In contrast, the optimal tax increase between 7.3 and 14.5 percentage points when human capital is accumulated with LBD, as opposed to exogenously. Taken as a whole, these findings indicate that not only whether human capital is accumulated exogenously or endogenously, but also the specific form of endogenous human capital accumulation can have important implications for the optimal capital tax.

Working Papers

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Optimal Public Debt with Life Cycle Motives
with Erick Sager
Press: Business Week

In a seminal paper, Aiyagari and McGrattan (1998) find that it is optimal for the U.S. government to hold a large amount of public debt. Their point of reference is a standard incomplete markets model with infinitely lived agents, in which the optimality of public debt derives from how an increase in the interest rate encourages more steady state precautionary savings. This paper revisits this result in a life cycle model and finds that public debt's insurance enhancing mechanism is, now, severely limited. While public debt increases the average infinitely lived agent's ex ante wealth, it has much less benefit in a life cycle model since agents enter the economy with no wealth. Thus, instead of debt being optimal as in the infinitely lived agent mode, when a life cycle is introduced it is optimal for the government to save on the order of magnitude of 59% of output. Furthermore, we find that not accounting for life cycle features when solving for optimal policy reduces welfare by nearly one-half percent of expected lifetime consumption.

An Extensive Look at Taxes: How does endogenous retirement affect optimal taxation?

This paper considers the effect on optimal tax policy of including endogenously determined retirement in a life cycle model. Because of two changes to the Frisch labor supply elasticity, endogenous retirement causes the optimal capital tax to increase by more than seventy percent. First, endogenous retirement increases the overall aggregate Frisch labor supply elasticity since agents can change their labor supply, not only on the intensive margin, but also, on the extensive margin. In response, the government lowers the labor tax and increases the capital tax to reduce tax policy distortions. Second, since the choice to retire is more relevant for older individuals, endogenous retirement disproportionately increases an agent's Frisch labor supply elasticity when he is older compared to when he is younger individuals. Ideally, the government would decrease the relative labor income tax on individuals when they are older. If age-dependent taxes are not available then the government mimics such a tax policy by further increasing the capital tax. I find that in my benchmark specification the welfare lost from not accounting for endogenous retirement when determining the optimal tax policy is equivalent to approximately 0.6 percent of total lifetime consumption.

Research in Progress

The Distributional Effects of Monetary Policy in a Life Cycle Model
with Aeimit Lakdawala and Tobias Cwik

A growing literature studies the contribution of monetary policy actions to inequality. We add to it by building a life cycle model that is used to understand the distributional effects of monetary policy. In the life cycle model, agents endogenously determine consumption, savings, and their portfolio in the face of idiosyncratic income shocks, uncertain mortality, aggregate productivity shocks, and monetary policy shocks, which gives rise to inequality both within and between the cohorts. The inclusion of a life cycle creates a setting where monetary policy can affect inequality through three potential channels. First, there is heterogeneity in sources of income related to where an agent stands in his life cycle. In particular, young agents tend to rely more heavily on labor income relative to the old. Changes in monetary policy have a differential impact on labor income relative to financial income thereby affecting inequality. Second, an agent's portfolio allocation changes with the life cycle. Young agents are more likely to invest in risky assets, while older agents tend to choose a portfolio which includes less risk. Monetary policy can have a disproportionate effect on the returns in each of these types of assets. Third, agents tend to transition from net borrowers to net savers as they age and a change in interest rates can have disproportionate effects on borrowers versus savers. This paper aims to quantitatively assess the importance of each of these channels in a computational overlapping generation model. In this framework we conduct two experiments. First, we consider the dynamic effects of a monetary policy shock on inequality. Second, we investigate the distributional consequences of an adverse aggregate TFP shock on inequality under different monetary policy rules.

The Aggregate Implications of Labor Supply Near Retirement
with Jose Mustre-del-Rio

A stylized view of labor supply late in life is that workers abruptly cut hours worked when transiting into retirement. This characterization ignores the possibility of partial retirement whereby individuals gradually decrease hours worked before reaching full retirement. We document the quantitative importance of these transitions late in life and then consider what classes of life cycle models can generate them. We find that otherwise standard models with age-dependent differences in the disutility of labor or differences in the disutility of working full versus part time can generate these transitions. Importantly, these models are consistent with a flat wage profile late in life, whereas standard models require wages to decrease in order to generate retirement. We then consider the implications of these more realistic formulations of retirement for the measurement of wage volatility.

Pareto Improving Tax Reforms in a Life Cycle Model
with Kent Smetters

Previous Research

Decomposing Inflation
(Federal Reserve Bank of Atlanta Economic Review, First Quarter, 2004)
Press: WSJ NYT

Recent declines in U.S. core inflation measures have prompted a renewed effort to understand inflation dynamics. Since late 2001, core consumer inflation rates have declined to levels not seen since the early 1960s. Core inflation as measured by the consumer price index (CPI) declined to 1.1 percent (year-over-year) by the end of 2003 while the core personal consumption expenditures price index (PCEPI) moved below 1 percent. This decline in measured inflation rates, coupled with uncertainty about future demand conditions, generated concern and debate among analysts and policymakers about near-term inflation prospects. In this article we provide a precise decomposition of the inflation rate by calculating the percentage point contributions of major consumer expenditure categories to core inflation measures over time. This technique provides a wealth of information concerning aggregate inflation behavior in a concise way, enabling us to describe the composition of inflation at any point in time. A particularly important benefit of this method is that it allows us to distinguish broad-based changes in inflation from changes due to relative price movements of a few components.