Tax progression under collective wage bargaining and individual effort determination[Die Wirkung progressiver Besteuerung bei kollektiven Lohnverhandlungen und unbeobachtbarem individuellen Arbeitseinsatz]

In this paper, we study the impact of tax policy on wage negotiations, workers’ effort, and employment when effort is only imperfectly observable. We show that the different wage-setting motives – rent sharing and effort incentives – reinforce the effects of partial tax policy measures but not necessarily those of more fundamental tax reforms. We show that a higher degree of tax progression always leads to wage moderation, but the well-established result from the wage bargaining literature that a revenue-neutral increase in the degree of tax progression is good for employment does not carry over to the case with wage negotiations and imperfectly observable effort. While it remains true that introducing tax progression increases employment, we cannot rule out negative employment effects from an increase in tax progression when tax progression is already very high.