Tidiane is a postdoctoral researcher at the University of Lugano (USI) in Switzerland. He is on leave to the NBER.
He studied economics at the Paris School of Economics. In 2018, he obtained a PhD in economics from the University of Lyon in the GATE CNRS.
His main areas of research include public economics, urban economics, and public policy evaluation with a focus on local jurisdictions. He uses a wide variety of methods, including applied theory, reduced-form empirics, and structural estimation.
He studied the importance of the urban setting for different local policy instruments, such as taxes on households and businesses, and public goods and services. He is also interested in the empirical identification of tax competition. His recent research focuses on welfare effects of local policy determination.
News
- From September 2022, Tidiane will be joining the NBER as a postdoctoral fellow to work on tax competition and the rise of local tax havens.
- Tidiane presented his Job Market Paper « The Marginal Value of Public Funds in a Federation »
at the 2022 NBER conference on the Economic Effects of Tax Competition.
The Marginal Value of Public Funds in a Federation
Abstract
Our objective is to establish and provide a framework for quantifying the welfare effects of fiscal policies in an open economy, with an emphasis on state and local governments in a federalist system. To do this, we develop a model of fiscal policy with benefit-spillovers, firm mobility, and household mobility effects from changing taxes and expenditures among interacting local jurisdictions. We then derive how mobility and spillovers influence the marginal value of public funds (MVPF). Because a federal planner internalizes interjurisdictional externalities, the MVPF for a federal and local planner can diverge substantially, and we derive theoretical conditions for when the local MVPF will be the larger or the smaller. We provide guidance on the additional empirical components of the marginal value of public funds necessary to understand the welfare effects of policies in a federalist system. Finally, we illustrate the key differences of social and local MVPFs using empirical applications to decentralized wealth taxation, bidding-for-firm subsidy competition, and education spending.
- « Taxes, traffic jam and spillover in the metropolis » has been awarded the 2019 Graduate Student Paper Award by the North American Regional Science Council, NARSC.
- « Tax competition within metropolitan areas » has been awarded the 2019 PhD Prize
by the French Economic Association, AFSE.

The 2019 AFSE PhD Prize has been awarded to Tidiane Ly for his thesis entitled “Tax competition within Metropolitan areas”, conducted at the University of Lyon 2 under the supervision of Florence Goffette-Nagot and Sonia Paty. The jury was really impressed by the originality, the quality and the rigor of the work carried out. The jury also greatly appreciated Tidiane’s wish to provide policy recommendations from his theoretical investigations and findings. Indeed, his thesis helps municipalities and lower-level jurisdictions in their policy instrument choice, and suggests that reforming the local institutional context requires to account for the specific responses of local governments.
- Tidiane received the qualification of Maître de conférence (Assistant professor) by the CNU (National council of the University).
- « Ownership incentives and housing affordability: Evidence from France » is available as a working paper, n°03-2021 ERUDITE, 2021
Ownership incentives and housing affordability: Evidence from France
Abstract
Are ownership incentive policies inevitably accompanied by detrimental inflationary effects?
To address this issue, we develop a theoretical model in which owners of new housing benefit from a homeownership subsidy or a rental investment incentive. We show that while both incentives increase the price of the new housing, they reduce old housing prices and have an ambiguous impact on the average housing price. These effects result from residential spillovers from the old housing market to the new housing market. We test these findings empirically by exploiting a 2014 French reform in the metropolitan area of Lyon which intensified both incentives. Difference-in-difference estimates confirm our theoretical predictions: two years after the reform, the price of new housing increased by 30% and the price of old housing decreased by 7%. Taking both markets together, the overall effect is non-significant. The share of new housing transactions increased by 25%.
- « Local taxation and tax base mobility : Evidence from France » has been published in Regional Science and Urban Economics.
Local taxation and tax base mobility : Evidence from France
Abstract
This paper investigates the impact of tax base mobility on local taxation. First, we develop a theoretical model in order to examine the connection between local business property taxation and tax base mobility within a metropolitan area. We and that, in the presence of a budget compensation, decreasing capital intensity in business property tax base, composed of capital and land, increases the business property tax rates and decreases the tax rates on residents. We test this result using a French reform which changed the composition of the main local business tax base in 2010. Difference-in-difference estimations show that in 2010, the reduction in tax base mobility indeed resulted in a 14% rise in business property tax rates and a reduction in housing tax rates of 1.3%, compared to pre-reform average levels.