This study investigates whether working time accounts affect the performance of German establishments based on the Establishment Panel from the Institute for Employment Research. The major results are: productivity and investments are positively correlated with working time accounts. No significant effects of working time accounts can be detected on wages and on operating surplus. On average, we find a tendency towards negative effects on profits. This result is less likely in phases of low product demand and for export-oriented, large establishments with a high share of skilled workers. Under strong sales fluctuations, we find positively significant effects on the operating surplus. JEL: C22, D21, J21, J22, J24