Claus Thustrup Kreiner

University of Copenhagen, CEBI, and CEPR

Daniel Reck

London School of Economics

Peer Ebbesen Skov

Auckland University of Technology and RFF

We are grateful for discussions with John Bound, Charlie Brown, Henrik Kleven, Etienne Lehmann, Alan Manning, Niels Johannesen, Emmanuel Saez, Mike Mueller-Smith, Juan Carlos Suárez Serrato, Joel Slemrod, Jeff Smith, Isaac Sorkin, Johannes Spinnewijn, Andrea Weber, and two anonymous referees. Jakob Jul Elben provided excellent research assistance. We are grateful to the Danish tax administration (SKAT) for providing monthly earnings data and to the Ministry of Teaching and Education (Ministeriet for Børn, Undervisning og Ligestilling, Styrelsen for It og Læring) for providing data identifying apprentices. We also thank the Confederation of Danish Employers for providing information about wage agreements and legal rules. Financial support from the Economic Policy Research Network and the Rockwool Foundation Research Unit is gratefully acknowledged. The activities of the Center for Economic Behavior and Inequality are financed by a grant from the Danish National Research Foundation.

A supplemental appendix is available online at http://www.mitpressjournals.org/doi/suppl/10.1162/rest_a_00825.