India notifies ‘One Nation, One Time’ rules for IST

The Indian government has notified the Legal Metrology (Indian Standard Time) Rules, 2026, as part of the ‘One Nation, One Time’ initiative. These rules, which will take effect 180 days after publication in the Official Gazette, aim to establish Indian Standard Time (IST) as the common, legally recognized, and traceable time reference for the country.

The framework is designed to support critical sectors that rely on precise time synchronization, including telecommunications, financial transactions, digital payments, power grids, transportation, data centers, and government information systems. The initiative also addresses cybersecurity by providing accurate timestamps necessary for correlating events during cyber incidents and enhancing security monitoring.

To ensure nationwide reach, CSIR-NPL, ISRO, and the Department of Legal Metrology have established secondary timescales at five Regional Reference Standard Laboratories in Ahmedabad, Bengaluru, Bhubaneswar, Faridabad, and Guwahati. These laboratories maintain continuous traceability to the IST managed by CSIR-NPL. Additionally, CSIR-NPL provides IST traceability to ISRO for the NavIC system to enable satellite-based dissemination.