<h1>Mandatory use of Indian Standard Time requires synchronization of all legal, commercial, digital and administrative systems.</h1> The government will mandate exclusive use of Indian Standard Time for all legal, commercial, digital and administrative activities through the Legal Metrology (Indian Standard Time) Rules, 2025, requiring synchronization with IST, prohibiting alternative time references except where authorised, and implementing a national Time Dissemination infrastructure of five Regional Reference Standard Laboratories equipped with atomic clocks and secure NTP/PTP protocols to ensure millisecond to microsecond accuracy, traceability, and mitigation of cybersecurity risks posed by foreign timing sources.