Hjalte Fejerskov Boas

I am a postdoctoral researcher at CEBI (Center for Economic Behaviour and Inequality) and the Department of Economics at University of Copenhagen.
I received my PhD in May 2025 under the supervision of Professors Niels Johannesen and Claus Thustrup Kreiner. During my PhD I visited Paris School of Economics, hosted by Gabriel Zucman.

My research revolves around international taxation and public finance:
How should governments design tax systems in a globalized and digitalized world?

CV: Available here

Email: hfb@econ.ku.dk

Mobile: (+45) 28 26 41 48

X: https://twitter.com/Hjaltefb, BSky: Bsky.app/hjaltefb

Google Scholar: Link

Research

Working papers

Taxing Capital in a Globalized World: The Effects of Automatic Information Exchange | with Niels Johannesen, Claus Thustrup Kreiner, Lauge Truels Larsen, and Gabriel Zucman

NBER Working Paper 2024

Media coverage: Vox EU, Zetland

Abstract: In the second half of the 2010s more than 100 countries—including all large offshore financial centers—started to automatically exchange bank information with foreign tax authorities. This informational big-bang marks a break with the situation of offshore bank secrecy that prevailed before. We study its effects on tax compliance by analyzing the universe of information reports sent by foreign banks to Danish authorities, matched to population- wide micro-data on income, wealth, and cross-border bank transfers. In response to the automatic exchange of bank information, tax evaders may repatriate previously undeclared offshore wealth, they may start to self-report offshore income to the tax authorities, or the tax authorities may detect their evasion in audits that use the new information reports. Using a variety of research designs, we find large compliance effects along all these margins, with the largest response coming from repatriation of wealth. Overall we estimate that the automatic exchange of bank information has closed about 70% of the offshore tax gap. These results highlight the power of international cooperation to improve tax compliance in a globalized world.

Presentations: OECD JITSIC 2025, OECD Tax Gap Conference 2023, EU Tax Observatory Seminar, EPRN Conference 2022, OFS Workshop on Empirical Analysis of Tax Policy 2022, the IRS, the Norwegian Tax Agency, the German tax agency, the Danish Tax Agency, the Danish Ministry of Taxation.

Enforcing Taxes on Cryptocurrencies | with Mona Barake

CEBI Working Paper 2024, EU Tax Observatory Working Paper

Awards: Heinz-König 2nd prize. ZEW - Leibniz Centre for European Economic Research

Media coverage: Taxnotes, Cryptonews.com

Abstract: Cryptocurrencies pose substantial challenges to tax enforcement due to their anonymous and decentralized properties, undermining conventional regulatory practices. We study the impact of an ambitious new enforcement initiative aimed at addressing these challenges: domestic third-party reporting of crypto income. We estimate tax compliance and behavioral responses to this new policy by combining unique Danish microdata from domestic crypto platforms, administrative tax records, and cross-border bank transfers. Despite the introduction of domestic third-party reporting, over 90% of crypto investors do not declare crypto income. Moreover, we identify a significant and persistent evasion response to the policy as investors shift trading activity from domestic platforms, subject to third-party reporting, to foreign platforms outside regulatory reach. Our findings underscore the limits of domestic enforcement strategies in addressing tax evasion for decentralized, borderless assets like cryptocurrencies, highlighting the need for international coordination.

Presentations: EPRN Conference 2025, Barcelona Workshop on the Economics of Taxation 2025, CESifo Public Economics Conference 2025, Oxford CBT Doctoral Conference 2024, IIPF 2024, The Danish Economic Society Congress 2024, CEBI Lunch Seminar, DGPE 2023, the Central Bank of Denmark, the Danish Tax Agency.

Work in progress

The transparency dividend: Dynamic effects of tax audits on offshore income | with Niels Johannesen, Claus Thustrup Kreiner, Lauge Truels Larsen, and Gabriel Zucman

Preregistration

Teaching

Lecturer:

2024: Introduction to Social Data Science
2022: Introduction to Social Data Science

Teaching assistant:

2021: B.Sc. Economics in Society