Théo Valentin

Théo Valentin

PhD Candidate in Economics at CREST/ENSAE/IP Paris

About me

I am a 4th year PhD candidate at CREST, ENSAE Paris, Institut Polytechnique de Paris under the supervision of Pierre Boyer and Michael Visser since September 2022. I visited the University of California, Berkeley, hosted by Emmanuel Saez during the 2025 Spring semester.

My research lies in the field of Public Economics and especially taxation where I combine both theoretical and applied approaches.
I am also very interested in Political Science and Social Choice.

Contact: theo.valentin@ensae.fr

Working papers

  • A Costly Transfer: Attention, Avoidance and Entry after a Corporate Tax Cut
    Do corporate tax cuts achieve their aim once the full range of firm responses is accounted for? I study a 2001 French reform that introduced a reduced corporate rate on profits below a threshold, and use exhaustive administrative data to measure firms’ real, avoidance, extensive, and attention responses that I integrate in a welfare framework. I find that the response of incumbent firms is almost entirely an accounting phenomenon: real activity, i.e. sales, employment, and payouts, does not move detectably, and the implied elasticity of reported corporate income is small, rising from 0.07 to 0.11 over the post-reform period as firms learn. The reform exhibits, however, a sizable increase in corporate entry of 38% relative to personal entry. Yet, a fraction of these new entries are split entities, personal-form incumbents creating corporate entities to shift income. Exploiting a French reporting requirement that lets me measure attention directly, I estimate that 21% of firms fail to apply the new schedule in the first year, with inattention disappearing within three years and accounting for 74% of the elasticity’s short-run attenuation. Inattention is costly and is equivalent to a 25% surtax on income relative to attentive firms. Together, these results imply that the reform’s return is concentrated on the entry margin rather than the inframarginal transfer to incumbents, which is costly but yields no detectable effect other than avoidance.

Paper presented at: UC Berkeley Public Finance Seminar (Berkeley, 2025), Center for Business Taxation Doctoral Conference (Oxford, 2025), UC Santa Barbara Brown Bag Seminar (Santa Barbara, 2025), University of Utah Lunch Seminar (Salt Lake City, 2025), EEA (Bordeaux, 2025), PSE Applied Economics Seminar (Paris, 2024), CESifo Public Economics Area Conference (Munich, 2024), ZEW Public Finance Conference (Mannheim 2024), The 80th Annual Congress of the International Institute of Public Finance (Prague, 2024)

  • Taxing Digital Addiction
    A substantial fraction of social media consumption relies on users’ behavioral biases. Yet as opposed to standard sin goods, e.g. tobacco and sodas, they are freed from corrective taxation. This paper develops a model of optimal taxation of a monopoly platform running a social media that jointly invests in an addictive technology and sets its ad-load. While generating consumer surplus, the social media harms users through overconsumption from addiction and harms non-users through negative consumption externalities. Because addiction investment is observable only by the platform, the social planner relies on a tax on total engagement as an indirect corrective instrument. A key friction is that the platform can offset the tax by adjusting its ad-load, limiting its effectiveness. I characterize the optimal tax through a sufficient statistics formula: the tax equals a welfare-weighted sum of the elasticities of addiction, ad-load and engagement to the tax. When the welfare gains of reducing addiction are large, the tax rate reaches its upper bound through the platform’s participation constraint and the social planner optimally extracts all platform surplus.

Awards: Best Paper Award of the 9th Doctoral Workshop on the Economics of Digitization, sponsored by CESifo.

Paper presented at: CREST Internal Seminar (2026), Doctoral Workshop on the Economics of Digitization (CESifo, Telecom Paris, TSE, 2026)

  • Charitable Giving, Tax Incentives and Tax Consent, with G. Fack, B. Garbinti, J. Goupille-Lebret
    Charitable giving is widely subsidized through the tax system, and the design of these subsidies relies heavily on estimates of the tax-price elasticity of giving. Yet charitable tax incentives differ along dimensions beyond their generosity, including which tax liabilities they offset and which organizations they make eligible. In this paper, we study wealthy taxpayers, who can simultaneously reduce their tax liabilities through charitable giving via both an income tax credit and a wealth tax credit in France. We investigate the existence of resistance to wealth taxation, which can generate responses to changes in the wealth tax credit that are disproportionate relative to the statutory price change: a household that donates instrumentally to reduce its wealth tax may drastically reduce its giving when the wealth tax credit disappears, rather than substituting toward the income tax credit. We provide empirical evidence of this large sensitivity to the wealth tax deduction exploiting two complementary reforms to the French tax system. The 2011 and 2018 reforms changed wealthy taxpayers’ access to a 75 percent wealth tax credit for charitable donations while leaving unchanged the existing 66 percent income tax credit. Combining these reforms with exhaustive French administrative tax records, we show that losing access to the wealth tax credit leads to a large decline in total charitable giving and little substitution toward the income tax credit. The implied price elasticity of donations ranges from $-1.6$ to $-2.0$, consistent across both reforms and different segments of the wealth distribution. This large response is difficult to reconcile with existing estimates of the income-tax-price elasticity of giving, and is consistent with the existence of wealth tax resistance among wealthy donors. Our findings suggest that the effectiveness of charitable tax incentives depends not only on their generosity but also on the tax they offset and the organizations they subsidize.

Paper presented at: ERC PARTICIPATE Closing Conference (SciencesPo, 2026)

Selected work in progress

  • Optimal Corporate Taxation with Welfare Weights
  • Optimism, Tax Simplicity and Firm Entry
  • The Puzzle of Consensus: A Model of Deliberative Mini-Publics
  • Comparing the Costs: Assembly-Based Direct Democracy and Representative Electoral Democracy, First Evidence from France

Non-academic Publications & Papers

Curriculum Vitae

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TA sessions

  • Econometrics 2, ENSAE Paris, Pr. Michael Visser (Graduate level, Spring 2023)
  • Econometrics - 3A CI/MS, ENSAE Paris, Pr. Bertrand Garbinti (Graduate level, Fall 2022)
  • Econometrics 1, ENSAE Paris, Pr. Xavier d’Haultfoeuille (Graduate level, Fall 2022)
  • Industrial Organization, Université Paris Descartes, (Undergraduate level, Spring 2021)