Indian Standard Time (IST) must be used nationwide for legal, administrative, commercial, and other official reasons, according to the government's Legal Metrology (Indian Standard Time) Rules, 2026.
The regulations were announced on August 27 by the nodal consumer affairs ministry, but they won't take effect until 180 days after they are published in the official gazette. This will give businesses, institutions, and government departments time to coordinate their systems.
The change coincides with an increasing reliance on digital and technology-based systems that rely on precise and synchronized time stamps, such as banking, payments, telecommunications, railroads, power grids, and computer networks.

The campaign for a consistent national time standard was sparked by the ministry's claim that discrepancies between the various time sources now in use could have an impact on the coordination and documentation of such efforts.
According to a statement from the ministry, the common time reference is anticipated to facilitate precise time-keeping in power systems, accurate time-stamping of banking and digital payment transactions, coordination among railroads, airports, and other transportation systems, dependable operation of telecommunication and internet networks, maintenance of government and legal records, and coordination of emergency and other time-critical services.

Make an effort to use Indian timing sources
The regulations' emphasis on lowering reliance on foreign satellite-based time sources—which are currently essential to a number of vital systems—is one of their main features.
In order to distribute correct IST through Indian institutions and legal metrology laboratories, the government is constructing infrastructure.
For safe and dependable time distribution, the regulations also permit the use of NavIC, India's domestic satellite navigation system, in conjunction with other authorized Indian timing sources.

Trial of White Rabbit Technology
The ministry established a White Rabbit Technology-based IST Dissemination Demonstration Network at the Regional Reference Standard Laboratory (RRSL) in Bengaluru in July 2026 as part of the "One Nation, One Time" project.
IST can be spread across industries like banking, telecommunications, power, transportation, and digital governance, as demonstrated by the pilot.
In a separate demonstration, the ministry demonstrated safe IST transmission between RRSL Bengaluru and NSE Chennai in cooperation with CSIR-National Physical Laboratory, ISRO, SEBI, the National Stock Exchange (NSE), and BSNL.

Before the regulations go into force, the ministry stated that the 180-day transition period would provide stakeholders time to assess current systems, make the required technical improvements, and get ready for full implementation.