Full Answer

GTM server-side tracking demands significant developer investment. Initial configuration takes 40-80 hours covering container setup, tag migration, trigger configuration, and testing across all platforms. Ongoing maintenance requires 5-10 hours monthly for tag updates, debugging consent mode issues, monitoring data quality, and adapting to platform API changes. Over five years, that totals 340-680 developer hours. At $150/hour, developer costs alone reach $51,000-102,000—before adding any subscription or infrastructure fees.