Viewpoint: Empirical evidence and tax policy design: lessons from the Mirrlees Review

Abstract This paper examines the role of evidence in drawing up the recommendations for tax reform in the Mirrlees Review. The arguments are organised loosely under five related headings: (i) Key margins of adjustment. (ii) Measurement of effective tax rates. (iii) The importance of information and complexity. (iv) Evidence on the size of responses. (v) Implications from theory for tax design. Although the Mirrlees Review focuses on all aspects of tax reform, the focus is this paper is on the taxation of earnings with some examples drawn from the taxation of consumption and savings.     

A note on optimal income taxation,public goods provision and robust mechanism design

This paper extends the model of optimal income taxation due to Mirrlees (Mirrlees, J., 1971. An exploration in the theory of optimum income taxation. Review of Economic Studies 38, 175–208) and includes private information on public goods preferences. A mechanism design approach is used to establish the following result: If policies are required to be robustly implementable in the sense of Bergemann and Morris (Bergemann, D., Morris, S., 2005. Robust mechanism design. Econometrica 73, 1771–1813), then the optimality conditions in the extended model with uncertainty about tax and expenditure policies are the same as in the standard model of optimal income taxation. The paper provides a foundation for a widely-used assumption in public finance, namely that individuals optimize their behavior subject to a predetermined and commonly known tax system.     

Optimal marginal and average income taxation under maximin

Using the Mirrlees optimal income tax model under maximin, we derive fairly mild conditions for a decreasing marginal tax rate throughout the skill distribution with no bunching, a strictly concave tax function in income and a single-peaked average tax schedule. Assuming additive preferences and an isoelastic disutility of labor function, these tax profiles are implied by aggregate skills that are non-decreasing with the skill level. If preferences are quasilinear in leisure or in consumption, these tax profiles are also obtained under a large set of skill distributions.     

The impact of changing skill levels on optimal nonlinear income taxes

The impact of changing an individual's skill level on the solution to a finite population version of the Mirrlees optimal nonlinear income tax problem with quasilinear-in-leisure preferences is investigated. It is shown that it is possible to sign the directions of change in everyone's optimal consumptions and optimal marginal tax rates in response to such a change.     

Financing education using optimal redistributive taxation

In this article, the joint use of an income tax and public provision of education as instruments to achieve the government’s distributional objectives is considered. Individuals differ in innate labour productivity and in aptitude to acquire skills through education. Actual labour productivity depends on both innate skill and the amount of education received. Using a generalized version of the Mirrlees tax problem that incorporates these features, qualitative properties of an optimal tax schedule are investigated.     

Using Elasticities to Derive Optimal Income Tax Rates

This paper derives optimal income tax formulas using compensated and uncompensated elasticities of earnings with respect to tax rates. A simple formula for the high income optimal tax rate is obtained as a function of these elasticities and the thickness of the top tail of the income distribution. In the general non-linear income tax problem, this method using elasticities shows precisely how the different economic effects come into play and which are the key relevant parameters in the optimal income tax formulas of Mirrlees. The optimal non-linear tax rate formulas are expressed in terms of elasticities and the shape of the income distribution. These formulas are implemented numerically using empirical earning distributions and a range of realistic elasticity parameters.     

Optimal income taxation with tax avoidance and endogenous labour supply

I determine the optimal income tax schedule when individuals both choose endogenously their labour supply and have the possibility of avoiding paying taxes. Considering a convex concealment cost function, I propose a formula for the optimal marginal tax rate, that generalizes the formula of the standard Mirrlees model to the case of tax avoidance. I also show that the results obtained by Casamatta (2021) in the fixed income case hold true when labour supply is endogenous: with a low enough marginal cost of avoidance, it is optimal to let some taxpayers, located in the interior of the skill distribution, avoid taxes.     

On the optimal income taxation: Some further numerical results

Using numerical calculations we show in the optimal income tax model that a realistic value for the elasticity of substitution between consumption and leisure (?=0.5) leads to conclusions different from some of those drawn by Mirrlees (1971) and Atkinson (1973). The marginal tax rates are not so low and the shape of the tax schedule is for a great majority of the population substantially nonlinear. A new feature in our calculations is that both results come out without going to maximin, as done by Atkinson (1973). We study in special cases the locality of the zero limit of the marginal tax rate at the upper end of the ability distribution and we achieve a very definite conclusion: this result is really very local. We also present an interesting approximation result concerning the relationship between the level of the government revenue and the marginal tax rate for individuals with high ability. An important methodological remark analogous to Sen's critique on the ethical measures of inequality is made on the interpretation of optimal income tax calculations.     

Altruism,jealousy and the theory of optimal non-linear taxation

This paper studies optimal non-linear taxes in a world in which there is altruism and jealousy. A formula for optimal marginal tax rates is derived which turns out to be a simple and intuitively appealing extension of a result due to Mirrlees. The paper shows that in this sort of economy all of optimal tax theory's general results either no longer hold or need not hold, and it sets out appropriate modifications to standard tax rules.     

含有负所得税的最优所得税再研究

文章在借鉴已有最优线性和非线性所得税研究成果基础上,结合中国国情提出含有负所得税的最优非线性所得税模型(有缓冲地带),即修正的Mirrlees税收函数,进而得出一些与以往研究不同的结论,从而进一步发展和充实了最优所得税理论。这对于在目前我国日益扩大的收入分配差距尚未根本性扭转的背景下重新审视我国现有的税收政策,通过实施负所得税制度重构收入分配政策具有重要的参考价值和借鉴意义。     

Optimal nonlinear income taxation with learning-by-doing

This paper examines a two-period model of optimal nonlinear income taxation with learning-by-doing, in which second-period wages are an increasing function of first-period labour supply. We consider the cases when the government can and cannot commit to its second-period tax policy. In both cases, the canonical Mirrlees/Stiglitz results regarding optimal marginal tax rates generally no longer apply. In particular, if the government cannot commit and each consumer's skill-type is revealed, it is optimal to distort the high-skill type's labour supply downwards through a positive marginal tax rate to relax an incentive-compatibility constraint. Our analysis therefore identifies a setting in which a positive marginal tax rate on the highest-skill individual can be justified, despite its depressing effect on both labour supply and wages.     

Risky human capital and deferred capital income taxation

We study the structure of optimal wedges and capital taxes in a dynamic Mirrlees economy with endogenous distribution of skills. Human capital is a private, stochastic state variable that drives the skill process of each individual. Building on the findings of the labor literature, we construct a tractable life-cycle model of human capital evolution with risky investment and stochastic depreciation. In this setting, we demonstrate the optimality of (a) a human capital premium, i.e., an excess return on human capital relative to physical capital, (b) a large intertemporal wedge early in the life-cycle, and (c) a non-zero intratemporal wedge even at the top of the skill distribution at all dates except the last date in the life-cycle. The main implication for the structure of optimal linear capital taxes is the necessity of deferred taxation of physical capital. The average marginal tax rate on physical capital held in every period is zero in present value. However, expected capital tax payments do not equal zero in every period. Necessarily, agents face negative expected capital tax payments early in the life-cycle and positive expected capital tax payments late in the life-cycle.     

Optimal Dynamic Taxation with Distinctive Forms of Social Status Attainment

We examine the role of both consumption‐ and wealth‐induced social comparisons in setting dynamic optimal income taxation. Under complete information, state‐invariant labor income taxes are used to remedy the externality caused by consumption‐induced social comparisons, while state‐contingent capital income taxes are used to remedy the externalities caused by both consumption‐ and wealth‐induced social comparisons. Under incomplete information, distinct types of agents are subject to an identical marginal capital income tax, which removes social comparisons. To solve the information problem, low‐productivity agents could be subject to a lower marginal labor tax than high‐productivity agents, which contradicts the traditional result in the Mirrlees–Stiglitz models.     

Viewpoint: Innovations in the theory and practice of redistribution policy

Abstract We present a survey of key results from second‐best optimal redistribution theory and their implications for tax‐transfer policy. The core results include the Corlett‐Hague theorem, the Deaton conditions, the production‐efficiency theorem, the Atkinson‐Stiglitz theorem, and the Mirrlees‐Saez characterization of the optimal non‐linear income tax system. These have been augmented in recent years by optimal participation tax rates, the implications of involuntary unemployment, the use of unconventional instruments, such as minimum wages, in‐kind transfer, and workfare, and the optimal taxation of capital income and bequests.     

Global capital markets,direct taxation and the redistribution of income

Standard fiscal theory suggests that taxation should be heaviest on the least mobile factors of production – for both efficiency and revenue reasons. A shift in tax burdens from capital to labour as economies become globally integrated is thus justified. This theoretical tradition (founded by Ramsay and continued by Mirrlees and Lucas) assumes by construction that profit taxes reduce investment and growth; and while sensitive to inter-generational equity, sidesteps the issue of income distribution within generations. In contrast, starting from Keynes’ critique of these assumptions and building on modern endogenous growth models, it can be shown that profit taxation is not necessarily injurious to productive investment. In practice, moreover, the effect of globalisation has not been to reduce tax rates on capital, but rather to erode the tax base itself (i.e. ‘tax evasion’). Improved information exchange between tax authorities, which is now being driven by fiscal insolvency in developed countries, would allow tax incidence to be shifted so as to improve income distribution within OECD countries. Such cooperation could also permit the replacement of the current discretionary system of fiscal transfers from rich to poor countries (‘development aid’) by equitable sharing of global capital tax revenue.     

Accidental Bequests: A Curse for the Rich and a Boon for the Poor*

When accidental bequests signal otherwise unobservable individual characteristics, such as productivity and longevity, the population should be partitioned into two groups: those who do not receive an inheritance and those who do. The first tagged group receives a Mirrlees second‐best tax schedule; the second group, when its type is fully revealed, faces a first‐best tax schedule. Receiving an inheritance makes high‐ability types worse off and low‐ability types better off. High‐ability individuals face a bequest tax of more than 100 percent, while low‐ability types face a bequest tax that can be smaller, as well as larger, than 100 percent, and it might even be negative.     

Externality Policy Reform: A General Equilibrium Analysis

We characterize Pareto‐improving and equilibrium‐preserving policy reforms in a second‐best (Diamond/Mirrlees) world with a consumption externality. A counterintuitive finding is that, starting from an initial equilibrium with no direct quantity control on the externality, it is possible that all Pareto‐improving and equilibrium‐preserving directions of change require an increase in a negative externality. We provide intuition for these results by establishing a nexus between Guesnerie's approach to designing (tax) policy reforms and the standard Kuhn–Tucker technique for identifying the manifold of feasible Pareto‐optimal states, given the instruments available to the policy maker.     

A contribution to the theory of optimal utilitarian income taxation

The paper provides a new formulation of the Mirrlees–Seade theorem on the positivity of the optimal marginal income tax, under weaker assumptions and in a more general model. The formulation of the theorem is independent of whether the model involves finitely many types or a continuous type distribution. The formal argument makes the underlying logic transparent, relating the mathematics to the economics and showing precisely how each assumption enters the analysis.     

Union strategy and optimal direct taxation

Restrictions on working hours are more important in countries with a large welfare state. We show that this empirical observation is consistent with the strategic effects of such restrictions in a welfare state in the context of optimal direct taxation in the tradition of Mirrlees (1971) [Mirrlees, J.A., 1971. An exploration in the theory of optimum income taxation. Review of Economic Studies 38, 175–208]. Our results also apply to non-welfarist states that have income redistribution, but not in purely extortionary states.