This paper provides new micro-level evidence on how labor taxation shapes firm behavior, exploiting an EU-mandated payroll tax reform in Norway. Combining administrative and survey data, we find that firms facing larger tax increases sharply cut employment but also increased R&D spending, implemented labor cost-saving innovations, and adopted more automation. While these responses led to improvements in labor and total factor productivity within the firm, the firm’s labor share fell. These effects persisted even after the tax hike was unexpectedly reversed three years later, suggesting a lasting shift toward more capital-intensive production in response to higher labor costs.