Ministers have now ordered a cautious phase-out to begin on 30 June, starting in areas with very few RTS customers to avoid sudden disruption.
RTS meters were introduced in the 1980s and rely on longwave radio signals to switch electricity tariffs and control heating or hot water systems at different times of day.
With the signal infrastructure now reaching the end of its life, the plan had been to shut the system down entirely this summer.
But poor preparation by energy firms has forced a rethink.
As of the end of May, 314,935 RTS meters were still active across Great Britain. Nearly a third of them – 105,000 – are in Scotland, with many others in rural or hard-to-reach areas.
The government has insisted the new approach will avoid sudden cut-offs and give customers the support they need.
Energy Minister Miatta Fahnbulleh said: “We have stepped in to ensure that thousands of vulnerable consumers with RTS meters do not experience any sudden disruption at the end of this month. I will be watching suppliers closely to make sure they are doing everything they can to make sure the transition is as smooth as possible.”
Ofgem has confirmed it will closely oversee the process.
The first stage of the phase-out will last three weeks and impact no more than 600 homes. Areas will only lose signal once suppliers meet strict criteria for customer contact and support.
Charlotte Friel, Director for Retail Pricing & Systems at Ofgem, said: “Ofgem has been clear that customers must be protected at every stage of the phased area-by-area shutdown and we are spelling out to suppliers key requirements that must be met before an area loses its RTS signal.”
She added that the Taskforce set up to speed up meter upgrades has made progress. Upgrade rates have jumped from 1,000 a month to over 1,000 a day but warned that “it remains crucial that these meters are replaced urgently”.
Households will be contacted before any change takes place.
Most will be offered a smart meter which can perform the same peak and off-peak switching, ensuring minimal disruption. Those without signal for a smart meter will be offered alternatives.
The minister will meet Ofgem and Energy UK every fortnight to review progress with a special focus on Scotland and remote areas.
Customers with RTS meters are urged to contact their supplier and book a replacement appointment without delay.
