One Nation, One Time: Govt notifies draft Legal Metrology (IST) Rules, 2025 to synchronise time across India

The Union government has notified the draft Legal Metrology (Indian Standard Time) Rules, 2025, to establish Indian Standard Time (IST) as the uniform and mandatory time reference across the country.

The draft rules, issued by the Ministry of Consumer Affairs, Food and Public Distribution, mandate IST as the sole time reference for commerce, transport, public administration, legal contracts, and financial operations. It also prohibits the use or display of any other time format for official and commercial purposes, except with explicit government approval.

"Aiming towards ‘One Nation, One Time’ and achieving precision in Indian Standard Time (IST), the Department of Consumer Affairs, Government of India has undertaken a project in association with National Physical Laboratory (NPL) and India Space Research Organisation (ISRO) to disseminate IST with millisecond to microsecond accuracy," a government release said.

"The project aims to create technology and infrastructure to disseminate IST from five Legal Metrology laboratories across India."

Indian Standard Time is based on Coordinated Universal Time (UTC) with an offset of +5:30 hours, maintained by the Council of Scientific and Industrial Research-National Physical Laboratory (CSIR-NPL). The rules require the synchronisation of time-keeping devices through reliable sources like Network Time Protocol (NTP) or Precision Time Protocol (PTP).

To bolster cybersecurity, provisions for resilience against cyber-attacks and disruptions, including alternate terrestrial time sources and NavIC signals, have been incorporated.

The draft rules prescribe the procedure for synchronization, guidelines for implementation and standards for accuracy, ensuring nationwide alignment with IST and facilitating improved governance, cybersecurity and operational efficiency.

The rules also prescribe penalties for non-compliance and outline detailed procedures for synchronization and monitoring.

The use of alternative timescales will be permitted for specific purposes such as astronomy, navigation, scientific research, etc. subject to prior permission and compliance with government directives.

"By implementing these rules, the Government of India is taking a decisive step toward ensuring precise and uniform timekeeping across the country, paving the way for technological advancement, economic efficiency, and strategic security," the ministry said in a statement.