Debates over return-to-office mandates have intensified since the COVID-19 pandemic ended, though their economic implications remain poorly understood. Using large-scale resume data, we analyze how these policies affect employee tenure and seniority at three large U.S. tech companies: Microsoft, SpaceX, and Apple. Employing a distributional synthetic controls framework, we estimate a reduction in tenure and seniority at firms returning to the office. We extend the framework with a functional bootstrap procedure and prove its validity for constructing uniform confidence bands. Return-to-office mandates appear to drive senior employees away, posing a risk to firm productivity and innovation.