Two Bodies, One Decision
The International Bureau of Weights and Measures (BIPM) voted in November 2022 to stop inserting leap seconds into UTC by 2035. But that vote bound only the metrology community. The telecommunications standards that specify UTC for broadcast time signals, satellite navigation, and network synchronisation are managed by the ITU-R (International Telecommunication Union -- Radio communication). For the leap second abolition to take full effect across the global timekeeping stack, the ITU-R also needed to act.
WRC-23 in Dubai
The ITU-R convenes a World Radiocommunication Conference roughly every four years to review and revise the Radio Regulations, the international treaty governing use of the radio spectrum and satellite orbits. WRC-23 ran from 20 November to 15 December 2023 in Dubai. Among the agenda items was a revision to Recommendation ITU-R TF.460, which defines the relationship between UTC and UT1. The conference adopted a modified recommendation endorsing the BIPM timeline and extending the tolerance for UTC-UT1 deviation from 0.9 s to 1 minute.
Impact on GPS and Navigation Systems
GPS time is already continuous -- it does not observe leap seconds and currently runs 18 seconds ahead of UTC. GLONASS uses UTC directly. Galileo (EU) and BeiDou (China) also maintain their own offsets. After 2035, the number of leap-second offsets that navigation receivers must track will stop growing. The GPS-UTC offset will remain frozen at whatever it is in 2035 (currently 18 seconds) for the foreseeable future, simplifying receiver firmware and improving interoperability between constellation systems.
What Still Needs to Happen Before 2035
The BIPM and ITU-R have agreed on the end of leap seconds but not on the mechanism for handling accumulated UTC-UT1 drift after 2035. The allowed drift of one minute will take roughly a century to accumulate. Before that happens, a "leap minute" or some other adjustment will be needed. The details of that future mechanism are explicitly left to the BIPM and ITU-R to decide at a later date -- likely at WRC-27 in 2027. For developers, the practical implication is that no new leap seconds will be inserted after 2035.