Since the COVID-19 pandemic, telework has become a permanent feature of labor markets, with 20% of French workers now teleworking 2-3 days per week. While prior studies have examined how telework affects spending near residences or workplaces, its net economic impact remains unclear: Does telework merely redistribute consumption, or does it reduce total economic activity? Using novel mobile phone location data and card transaction records from Lyon metropolitan area, France’s second-largest region, we provide the first two-sided assessment of telework’s effects. We find that a 1% increase in home-based telework raises local spending by 1%, while a 1% increase in workplace absence reduces it by 1.3%, yielding a net 3% decline in aggregate consumption. Home-based gains offset only 57–72% of workplace losses, indicating incomplete substitution, a finding that challenges prior assumptions and suggests telework is a net economic shock. The effects are spatially heterogeneous: urban cores lose 6.8% in transactions, while residential suburbs gain. Sectorally, restaurants decline by 24%, but bars and food retail benefit. These results imply that telework is reshaping urban economies, with significant implications for urban planning, retail policy, and economic geography.