Centre notifies Legal Metrology Rules to enforce IST

The government has notified the Legal Metrology (Indian Standard Time) Rules, 2026, mandating IST as the legally recognised national time reference. Effective 180 days after publication, the rules establish a distributed architecture through CSIR-NPL, ISRO, and RRSLs to ensure reliable dissemination of IST across critical sectors.

New Delhi:  In a bid to develop modern digital and critical infrastructure, the government has notified the Legal Metrology (Indian Standard Time) Rules, 2026 — marking a significant step towards establishing Indian Standard Time (IST) as the common, legally recognised and traceable time reference for the country.

The rules comes into force 180 days from the date of their publication in the Official Gazette.

---

The initiative supports the government’s vision of “One Nation, One Time”, ensuring that critical sectors and digital systems across the country operate with a common and reliable time reference.

The rules provide a comprehensive framework for the generation, maintenance, dissemination and use of IST.

According to an official statement, telecommunications, financial transactions and digital payments, power grids, transportation, data centres, government information systems and other critical services depend on accurate time synchronisation and reliable time stamps.

A common national time reference also has an important cybersecurity dimension.

Accurate time stamps are essential for correlating events across multiple systems during cyber incidents and for effective security monitoring.

The CERT-In Guidelines on Information Security Practices for Government Entities, 2023, recommend synchronisation of ICT systems with standard time sources including NPL and NIC, said the statement.

Recognising that making IST a legal reference must be accompanied by adequate availability and geographical reach of traceable time, CSIR-NPL, ISRO and the Department of Legal Metrology under the MoCA jointly established secondary timescales at five Regional Reference Standard Laboratories (RRSLs) located at Ahmedabad, Bengaluru, Bhubaneswar, Faridabad and Guwahati.

These secondary time scales are continuously traceable to IST maintained by CSIR-NPL, thus creating a distributed national architecture for reliable dissemination of IST.

Moreover, CSIR-NPL also provides traceability of IST to ISRO for the NavIC system, enabling satellite-based dissemination of Indian Standard Time and strengthening the availability and resilience of national timing services.

IST can be disseminated through network-based technologies such as NTP and PTP, and satellite-based systems including NavIC.

High-precision optical fibre-based technologies such as White Rabbit are also being tested.

This distributed architecture provides flexibility for users ranging from ordinary ICT systems to applications requiring highly precise time and frequency synchronisation.

The Rules provide the legal framework for wider adoption of a common Indian time reference, while the infrastructure established by NPL, NIC, ISRO and the RRSL network provides the technical capacity required for its implementation.

The Legal Metrology (LM) Department under the Ministry of Consumer Affairs (MoCA) is the regulatory and enforcement authority under the Legal Metrology framework, while the CSIR-National Physical Laboratory (CSIR-NPL), India’s National Metrology Institute, provides the scientific foundation and traceability for IST.