This paper examines five decades of Earned Income Tax Credit (EITC) expansions to estimate employment elasticities and inform future policy design. I construct a comprehensive accounting of changes in tax credits, public assistance, and the return to work, and synthesize evidence across prior studies using a unified framework. The analysis demonstrates how alternative modeling choices—such as how the return to work is measured or which employment estimates are used—generate substantially different elasticity estimates. I present a distribution of estimates across specifications and assumptions, summarized in a histogram of implied elasticities. While estimates vary widely--even for a given policy change and/or employment response--the central tendency is clear: employment elasticities for unmarried mothers average around 0.3.

The design of French income tax provides an approach for estimating tax elasticities of all kinds. Compared to natural experiment designs that analyse between-income variation (such as arising from tax reforms affecting certain income groups), the variation examined in this paper stems from differential within-income shifts to the tax liability function. This makes it possible to control for income without absorbing identifying variation and eases testing of the underlying assumptions. It also means that the complier population is larger, allowing for heterogeneity analyses across income distribution, gender and a range of socio-economic characteristics. Applying this strategy to data covering the universe of French income tax returns from 2003 to 2023 reveals considerable heterogeneity along all these dimensions.

This paper studies bunching at kink points of the effective marginal tax-benefit schedule, emphasizing the joint role of income taxation, social security contributions and benefits, informality, and labor-market frictions. Using matched employer-employee administrative data from Brazil, we combine empirical evidence and structural modeling. We document that bunching occurs only at the pension-benefit cap, with responses increasing with age and decreasing with firm size. We develop a theoretical framework building on Saez (2010) and Chetty et al. (2011) that incorporates the discounted value of future pension benefits into the effective marginal tax-benefit rate (EMTBR) and allows informal income to interact with formal labor-market frictions. Calibrating the model to the data, we find that the EMTBR declines with age prior to retirement, firm-size-dependent frictions explain why bunching occurs only at the largest kink, and the structural elasticity of labor supply with respect to the EMTBR is 0.47.

Using comprehensive administrative tax return data from 2017–2024, this study examines how Kenyan taxpayers respond to personal income tax reforms. Applying a bunching approach around effective kink thresholds, the paper estimates excess mass and the elasticity of taxable income (ETI), while exploring differences across worker types and regions. The findings reveal strong bunching among self-employed individuals, with excess mass reaching 2.9 and ETI estimates up to 0.42. Unlike typical patterns in the literature, taxpayers consistently bunch above the kink, which may reflect cautious compliance behaviour or adjustment frictions. Behavioural responses intensify following reforms that make the kink salient. Regional heterogeneity is substantial, with taxpayers outside Nairobi exhibiting higher responsiveness than those within Nairobi. Regressions further show that bunching is not persistent at the individual level, as many taxpayers located near

the kink in baseline years subsequently move upward relative to the threshold.