Tuomas Kosonen VATT-14.jpg

Tuomas Kosonen

I'm Research Professor at VATT Institute for Economic Research in Helsinki, Finland. I have a PhD in economics from University of Helsinki. My research focuses on public economics and labor economics. My recent publications are on behavioral effects of consumption and income taxes.


A case for zero effect of sin taxes on consumption? Evidence from sweets tax reforms

with Sami Jysmä (LIER) and Riikka Savolainen (Newcastle)



Excise taxes are effective means to meet policy goals when they succeed in reducing consumption of the targeted goods, while VAT and sales taxes are effective when they create as little behavioral responses as possible. To provide novel answers to the question of when these conditions are met, we study a sweets and soda tax scheme in Finland providing us quasi-experimental variation in excise taxes by increasing taxes on sweets, soda and ice cream but leaving other sweet goods untaxed. Different reforms we study create variation also in how close substitutes the most similar non-taxed goods are to the taxed goods allowing us to examine the role of substitution as a mechanism explaining the main results. We have access to unique product- and week-level data on sales containing hundreds of millions of observations. Intriguingly, we find that without very close non-taxed substitutes the tax scheme did not create any discernible demand responses, but do create large responses when very close non-taxed substitutes are available. We explain the role of substitution with Gorman-Lancaster theoretical model and survey data on substitution preferences.


We provide evidence of discrete labor supply and study the broader implications of discrete responses for estimating earnings elasticities. We utilize an income notch and a reform that shifted the location of the notch to study labor supply mechanisms. We find transparent reduced-form evidence that this reform caused large earnings responses from a broad income range in the distribution, which is consistent with discrete labor supply. We then illustrate that conventional welfare-loss estimates can be downward-biased when labor supply is discrete instead of continuous.

What Goes Up May Not Come Down: Asymmetric Incidence of Value Added Taxes

with Youssef Benzarti (UCSB), Dorian Carloni (CBO) and Jarkko Harju (VATT) Journal of Political Economy, Vol. 128, No. 12, 2020.

This paper shows that prices respond more to increases than to decreases in Value-Added Taxes (VAT). First, we combine monthly commodity price data with information on VAT reforms across European countries from 1996 to 2015 to show that prices respond 3 to 4 times more to VAT increases than decreases. Second, we show that the asymmetry persists over several years. Third, we document several empirical features of this asymmetry that are inconsistent with the standard incidence model, such as distributional asymmetry. We provide evidence consistent with firm behavior driving the asymmetry.

The Impact of Foreign Acquisitions on Wages and Compensation

with David Autor (MIT), Matti Sarvimäki (Aalto) and Tuomo Virkola (EUI and LIER) 

Wages and exposure to foreign ownership in local labor markets



We study the effects of foreign takeovers on firm performance, skill premium and compensation practices following Finland's deregulation of foreign ownership in the mid-1990s. Firms taken over by foreign investors increase their sales, number of employees and wages in comparison to comparable firms that remain domestically owned. We find larger effects on wages at the industry and local labor-market level with an alternative identification strategy using foreign ownership patterns in Sweden to instrument acquisitions in Finland. 

The Effect of Home Care Allowance on Child Outcomes

with Jon Gruber (MIT), Kristiina Huttunen (VATT) 



We study the impacts of policy induced home care or day care decisions by parents on children’s short- and long-term outcomes. We are able to utilize regional and over time exogenous variation in child home care allowance that significantly increases incentives to stay at home and take care of children that are under the age of three in Finland. Our results show that home care allowance decreases maternal employment and negatively affects the early childhood cognitive test results at the age of five. On longer term we find that home care allowance increases likelihood of choosing vocational rather than academic secondary education track and increases youth crimes. However, we do not find any impact on the grades of children after primary school. The results are more pronounced in municipalities that have higher average child care quality. Supporting the home care versus day care mechanism we additionally utilize a day care fee reform that created exogenous variation in day care fees and affected child outcomes ways consistent with the mechanisms explained above. The results indicate that universal child policies can have substantial impact on the subsequent lives of children.

Missing Miles: Avoidance and Evasion Responses to Car Taxes

with Jarkko Harju (VATT) and Joel Slemrod (UMich) Journal of Public Economics, vol. 181, 2020.

We study tax avoidance and evasion responses to extensive import car taxes in Finland. We do this by exploiting a series of policy reforms in Finland, by utilizing novel third-party comparison information, and by analyzing a randomized control trial that varies the salience of the third-party information and a public disclosure program that renders less attractive car tax evasion achieved by overstating the mileage of imported used cars. The results suggest that car taxes in Finland induce car buyers to avoid some of the taxes by importing used cars from other countries without a high car import car tax. Moreover, we find systematic evidence of tax evasion in the form of “missing miles.” The tax evasion leads to a significant loss of tax revenue and is positively related to CO2 emissions and the tax rate. Increasing the salience of the anti-evasion initiatives reduced reported the overstatement of mileage.


Firm types, price-setting strategies, and consumption-tax incidence

with Jarkko Harju (VATT) and Oskar Nordström Skans (Uppsala)

Journal of Public Economics, vol. 165, pages 48–72, 2018

We analyze price responses to large restaurant VAT rate reductions in two different European countries and show that price responses in the short and medium run were clustered around two focal points of zero pass-through and full pass-through. Differences between independent restaurants and chains is the key explanation for this pattern. While nearly all independent restaurants effectively ignored the tax reductions and left consumer prices unchanged, a substantial fraction of restaurants belonging to chains chose a rapid and complete pass-through. In the longer run, prices converged, but primarily through a price reversion among chain restaurants. The stark difference in price responses cannot be explained by location, initial prices or other market-segment indicators such as meal or restaurant types. Further evidence on the use of round-number pricing, on price-change frequencies, and on pricing behavior during currency conversions suggests that the diverging price responses to consumption-tax reforms reflect fundamental differences in price-setting behavior between the two types of firms.