Almost Fare Free: Impact of a Cheap Public Transport Ticket on Mobility Patterns and Infrastructure Quality  (2024),
with Mario Liebensteiner, Jakob Losert, Florian Neumeier, Jörg Paetzold, Sebastian Wichert , Cesifo WP No. 11229, R&R at Journal of Public Economics.

Summary in German: ifo Schnelldienst

Summary in English: Econ Pol Forum

In 2022, Germany introduced a temporary 9-euro monthly ticket for unlimited local and regional public transport. We investigate its impact on mobility patterns, including increased public transport usage, reduced car traffic, and rail network congestion. Using difference-in-difference and event-study analyses with mobile network-based mobility, traffic volume, and rail traffic data, we find limited substitution between transportation modes, a strong increase in leisure train journeys, and notable adverse effects on rail infrastructure quality. These effects dissipate after the ticket’s expiration. Our study suggests caution regarding the expected environmental benefits of nearly fare-free ’go-anywhere’ public transport tickets, which are discussed in several countries. 

Monetary rewards for tax compliance: (When) are they effective? (2024), with Lilith Burgstaller, Annabelle Doerr, Cesifo WP No. 10211, R&R at Oxford Bulletin of Economics and Statistics

Summary in German: ifo Schnelldienst, 2023, 76, Nr. 02, 43-46 

Summaries in English: EconPol Forum 24 (1), CESifo, Munich, 2023, VoxEU column 

Media coverage: SWR Radio

We study the causal effects of household tax credits on the willingness to demand legally provided services using two survey experiments with 1.974 German homeowners. We vary the type of the tax credit, the refund rate, and whether the financial benefit is made salient. All tax credits increase the willingness to pay for offers with invoice. The effectiveness is highest when the tax credit is granted at source in combination with a high refund rate or when the financial advantage is made salient. The effect of salience is as high as the effect of increasing the rate of the tax credit by 10 ppts. However, we observe substantial free-riding: at least two thirds would have demanded an offer without invoice also without the subsidy.

Tax System Design,  Tax Reform, and Labor Supply (2024), with Katharina Pfeil, Matthias Kasper, Lars Feld, Cesifo Working Paper No. 11350 , R&R at Labour Economics

This study examines how tax system design and reform affect labor supply. We conduct an online experiment with 522 participants to assess labor responses to tax reforms that introduce or remove a notch, affecting after-tax income at either the lower or upper end of the income distribution. Our findings indicate asymmetric responses to tax reform as well as substantial heterogeneity at the individual level. In particular, we find an increase in labor supply in response to a tax reform only when the reform reduces the tax burden at the upper end of the income distribution. While, in the aggregate, labor supply adjusts on the extensive and intensive margins, we also find strong evidence of heterogeneity in individual responses, showing that the labor response is primarily driven by individuals directly affected by the reform. We examine the role of misperceptions at the individual level as well as fairness considerations in explaining these results. 

Does information on tax shifting shift tax preferences? (2025), with Lisa Windsteiger, Fabian Böhme (email me for a copy). 

In a survey experiment, we examine whether individuals’ tax attitudes change when they are informed about potential tax incidence channels. Using corporate taxation as an example, participants are told that taxes can be passed on via  consumer prices, wages, shareholder payouts, or investment. We find that providing information about consumer price or wage incidence significantly reduces individuals’ preferred corporate tax rates. In contrast, informing them about reduced shareholder payouts or investment has no significant effect. We observe a similar pattern using participants’ open-ended responses before the information treatment. Mediation analysis suggests that information about tax incidence influences tax preferences primarily by altering perceived personal costs, rather than through concerns about distributional fairness.

What Drives Refugees' Return After Conflict? (2025), with Joop Adema, Lasha Chargaziia, Yvonne Giesing, Panu Poutvaara, RF Working Paper 65/25. 

Refugees' decisions to return after conflict carry significant political and economic implications for the origin and host countries. We examine how conflict resolution, security, and economic conditions influence return decisions. To estimate the causal effect of post-war conditions, we conducted a conjoint experiment among 2543 Ukrainian refugees across 30 European countries. Respondents were asked how likely they would be to return to Ukraine under different hypothetical scenarios. Results show that territorial integrity and security guarantees are critical, while economic prospects and combating corruption also play an important role. Our findings suggest that targeted political and economic reconstruction policies can substantially influence post-conflict return. In the most optimistic scenario, the expected return rate is 47%; in the most pessimistic scenario, only 3%.

The absolute and relative gain of dishonesty (2024), with Benoit Le Maux (email me for a copy). 

We distinguish the absolute and relative gain of dishonesty by varying two payoff dimensions in a cheating game: the payoff level and payoff  difference between being successful or not. In our online experiment, dishonesty tends to decrease when the level of payoffs is higher and to increase when the absolute difference between payoffs  increases. Comparing the conditions with the lowest and highest relative gain, the number of reported successes decreases by one third of the standard deviation. Our results suggest that organizations should design reward schemes such that people earn a reasonable amount from not being successful and only a relatively small bonus from being successful.