This paper presents new evidence on the effects of retirement benefits on labor force participation decisions. The analysis is based on a mandated rule for employer-provided retirement benefits in Austria that creates discontinuities in the incentives for workers to delay retirement. The paper presents graphical evidence on labor supply responses and develops a conceptual framework that accounts for the dynamic incentive structure and for adjustment frictions. Using bunching methods, a semi-elasticity of participation is estimated, which ranges from 0.1 to 0.3 and is highest for incentives targeted at a delay in retirement by 6 to 9 months. (JEL D14, D91, H55, J22, J26, J65)