CSIR-National Physical Laboratory (CSIR-NPL), New Delhi, has been the custodian of Indian Standard Time (IST) since the inception of the laboratory. Trademark for IST® has been registered in 2024. However, time has not been legalised in India so far.

To synchronise time across the country, the Department of Consumer Affairs, Food & Public Distribution, through its Legal Metrology Department, has released the Draft Legal Metrology (Indian Standard Time) Rules, 2025, for public consultation. The “One Nation, One Time” initiative aims to establish a comprehensive legal framework for defining, implementing and standardising Indian Standard Time (IST®) as the sole and mandatory time reference across all sectors nationwide. Introducing these rules is a major step toward nationwide time uniformity, ensuring that all legal, administrative, financial, and commercial activities operate with a single, accurate time reference.

Time synchronisation is crucial in today’s digital and interconnected world. Inconsistent time references across sectors can lead to inefficiencies, security risks, and operational challenges.

Different organisations and institutions in India currently rely on various time sources, such as GPS signals or independent time servers, creating inconsistencies. Only one legally recognised time reference will ensure alignment across digital systems, businesses, and government operations to enhance efficiency, security, and trust. The draft rules require all government departments, businesses, and commercial entities to synchronise their systems with IST®, prohibiting alternative time references unless legally permitted. Successful implementation will benefit various sectors, especially financial services (trading, digital payments), telecommunication (5G and 6G), smart power grids, and cyber security (diagnostics, secure operations).

CSIR-NPL: Custodian of Indian Standard Time

CSIR-NPL, India’s National Measurement Institute (NMI), is responsible (by an act of Parliament) for realising, maintaining, and disseminating IST®. IST® is generated using advanced atomic clocks and satellite links to ensure that it is traceable to Coordinated Universal Time (UTC), the international reference time, with an uncertainty of less than 3 nanoseconds.

The IST® is widely disseminated with millisecond accuracy with NTP (Network Protocol Service) servers at CSIR-NPL. Indian Space Research Organisation (ISRO) is being given traceability to IST®, with nanosecond accuracy, via satellite links for the Indian Regional Navigation Satellite System (IRNSS), also known as NavIC. NavIC will play a crucial role in enhancing India’s time dissemination capabilities and self-reliance in national time traceability satellite (GPS-free) links.

To enhance accessibility to IST®, secondary time laboratories are being established in five regional reference standard laboratories (RRSLs) by CSIR-NPL and ISRO, with funding from the Department of Legal Metrology. These labs, traceable to IST®, will function as regional time dissemination hubs, creating a robust network for nationwide synchronisation. Accurate time synchronisation is crucial even for emerging sectors like quantum communication, quantum cryptography and quantum computing.

Public Consultation and Future Implementation

The draft rules were recently released on the MoCA website for public consultation to address industry needs and potential challenges effectively and ensure smooth implementation. Once finalised, the rules will mandate strict compliance across all sectors, providing a legally enforceable framework for time synchronisation.

The Broader Impact of “One Nation, One Time”

The adoption of a unified time standard will
•    Strengthen digital infrastructure by enhancing cloud computing, AI, and IoT networks.
•    Boost economic growth through improved productivity and reduced losses caused by time discrepancies.
•    Enhance national security by securing data transactions and defence operations.
•    Improve public services such as government portals and transportation networks.

The role of CSIR-NPL is pivotal as the nation’s official timekeeper to ensure that IST® remains accurate, traceable, and aligned with international standards. The successful implementation of "One Nation, One Time" will streamline operations nationwide and reinforce India’s standing as a global leader in precision metrology and time synchronisation.