Tom Zawisza
tomasz.zawisza [at]

University College London
Gower Street
Tel: +44 (0) 20 7679 2000

Institute for Fiscal Studies
7 Ridgmount Street
Tel: +44 (0) 207 291 4800


British Academy Postdoctoral Fellow
University College London, United Kingdom



I am a British Academy Postdoctoral Fellow at University College London. I completed my PhD was at the Faculty of Economics, University of Cambridge, where I worked under the supervision of Professor Hamish Low, and was recently a Max Weber Fellow at the European University Institute in Florence, Italy.

My research focuses on analyzing the insurance and incentive effects of tax and welfare policy. I am looking at this problem from two perspectives: a theoretical one, where I model individuals as forward-looking agents making optimal saving and labour-supply choices; and an empirical one, where I attempt to identify structural parameters of models from the data.


(Work in progress) "Labor Supply and the Pension Contribution-Benefit Link" , with Eric French, Attila Lindner and Cormac O'Dea

Abstract: We estimate the labor supply response to a reform that switched the Polish pension system from a Defined Benefit (DB) to a Notional Defined Contribution (NDC) scheme. Central to this reform was a change the link between current pension contributions and future pension benefits. Only those born after December 31st 1948 were affected, creating a sharp cohort-based discontinuity in the contribution-benefit link for individuals in their 50s. Using administrative data on the universe of Polish taxpayers, we examine labor supply responses to the reform at ages 51-54, around 11-15 years before the normal retirement age. In line with the change in incentives, we find that the employment rate decreased by 2% in response to the policy change, which is consistent with an extensive margin elasticity of 0.33. These responses are driven by regions where the incentives had changed the most. Our results imply that changing the contribution-benefit link of public pensions can alleviate the labor supply distortions caused by social security contributions.

(Work in progress) "Identifying Intensive and Extensive Margins of Response to Tax Policy using Poland's 2009 Reform"

Abstract: In this paper I examine two crucial questions regarding the design of the optimal tax system, exploiting the 2009 Polish tax reforms for identification. Firstly, I contribute to the literature on elasticity of taxable income by providing estimates of taxable income elasticities which are robust to changes in year-to-year income dynamics, exploiting variation in marginal tax rates due to the 2009 reforms which occurred independently of an individual's position in the income distribution. Secondly, I examine the extensive-margin adjustment between the employment and self-employment tax base. In particular, I quantify the impact of changes in the differential in rates of taxation between the two tax bases on the propensity of taxpayers to declare themselves as employed or as self-employed individuals. This allows me to identify parameters in an extension of the Mirrlees (1971) model which I develop to include both intensive-margin adjustment and tax-base choice.

(Work in progress) "Political conflict, social inequality and electoral cleavages in Central-Eastern Europe, 1990-2018" , with Attila Lindner, Filip Novokmet and Thomas Piketty

Abstract: This paper analyses the electoral cleavages in three Central European countries countries—the Czech Republic, Hungary and Poland—since the fall of communism until today. In all three countries, the left has seen a prolonged decline in support. On the other hand, the “populist” parties increased their support and recently attained power in each country. We relate this to specific trajectories of post-communist transition. Former communist parties in Hungary and Poland transformed themselves into social-democratic parties. These parties' pro-market policies led to a gradual erosion of their traditional support. Meanwhile, the liberal right in the Czech Republic and Poland became representative of both high-income and high-educated voters. This has opened up space for populist parties and influenced their character, assuming more ‘nativist’ outlook in Poland and Hungary and more ‘centrist’ in the Czech Republic.

(Work in progress) "Saving Behaviour of Disability Insurance Applicants: Are Waiting Times Effective Screening Devices?", with Hamish Low and Luigi Pistaferri

Abstract: The paper examines the consumption and saving behaviour of Disability Insurance (DI) applicants using a life-cycle model. We include a two-dimensional health process which determines an individuals health, and has implications for the chances of succeeding at the application and appeals stage. Saving behaviour for disability applicants of different types is examined, testing the validity of the predictions of Golosov and Tsyvinski (2006). The model provides an explanation for higher saving rates observed among moderately or 'non-verifiably' disabled individuals. The paper finally asks whether the length of the compulsory time out of the labour force before making a DI application can improve the DI system in terms of the insurance-efficiency trade-off.

(Work in progress) "Disability and disability risk over the life-cycle"

Abstract: This paper estimates the dynamics of health using a dynamic panel factor model on data from the Health and Retirement Study (HRS). It finds that the many potentially collinear health indicators found in the HRS can be summarized into two underlying factors. The first of these corresponds to subjective health measures, such as self-assessed mobility, while the other corresponds to more objective measures of health-care utilization, such as the number of overnight hospital stays. The dynamics of the factors are estimated as an underlying VAR process, and the discreteness of the HRS health indicators is dealt with by assuming a multinomial functional form. The model as a whole is estimated using the Generalized Autregressive Score (GAS) approach of Creal, Koopman and Lucas (2013).

Policy-focused papers

"Banking Sector Efficiency in Sub-Saharan Africa", with Francois Boutin-Dufresne and Oral Williams, Journal of African Economies , 2014, 1-27.

Abstract: This paper examines the determinants of net interest margins in four regional blocks in Sub-Saharan Africa. Using bank-level data, we find that countries with a high level of operating costs, a high low level of non-interest income, a high ratio of equity to total assets and high treasury-bill interest rates have higher net interest margins. Moreover, high operating costs are associated with low measures of institutional quality and a small size of bank operations. We find support for the view that market structure is also partly responsible for high net interest margins in Sub-Saharan Africa, although quantitatively this effect is somewhat less important. High operating costs, high treasury-bill rates and a high ratio of equity to total assets and, indirectly, institutional factors such as the rule of law, are the most important factors in accounting for high interest margins in the East African Community, relative to other regions.