One in 10 Mid Devon households get a one-off payment to help with the cost of energy during winter, new figures show.
The number of households receiving the Warm Home Discount across England, Wales and Scotland rose by a quarter in 2023-24.
However, the Fuel Poverty Action charity said the scheme "is failing to protect those on the lowest incomes from fuel poverty".
The Warm Home Discount is a one-off payment of £150 designed to help lower-income and vulnerable households with their energy bills during the winter months. The scheme will reopen in October.
Department for Work and Pensions figures show there were 3,404 households in Mid Devon who received the rebate in 2023-24. They accounted for 9% of households in the area.
This was up from 7% the year before.
Across the three nations, 3.1 million households, or one in 10, had the discount added to their energy bill – an increase from 2.5 million in 2022-23.
However, Adam Scorer, chief executive of the charity National Energy Action, said too many vulnerable people are missing out altogether.
He said: "For households who receive a rebate, the Warm Home Discount can be a winter lifeline.
"But the rebate has only risen by £10 in over a decade. With an increase in bills likely this autumn, even those who still get the rebate now desperately need deeper support."
He added: "Low-income families who aren't on benefits or who live in marginally smaller or newer homes are no longer able to receive a rebate.
"For them, the scheme must feel like a cruel postcode lottery."
There were regional differences in the rates of households receiving the rebate. The North East had the highest rate at 16%, while the South East and Scotland had the lowest, at 8% and 4% respectively.
Matthew Cole, head of the Fuel Bank Foundation, said: "One of our three requests for the next government is that support is provided for households that can't afford to keep the lights or gas on.
"This can be because they don't have the money to pay for energy – especially over the winter heating period – or because they need to use higher than average levels of energy to get and stay warm. Often it is both."
He added: "Warm Home Discount does provide some of this support, but the current £150 does not cover the deficit that so many face.
"We hope the next government thinks more widely about the levels of support it needs to provide to those most in need."
In the South West, the rate went up from 7% to 9%.
Jonathan Bean, spokesperson for Fuel Poverty Action, said: "The Warm Home Discount is failing to protect those on the lowest incomes from fuel poverty.
"It doesn't even cover half of the cruel standing charges. And it ignores the four times higher unit costs that those with only electric heaters face.
"The new government urgently needs to bring in real protection from fuel poverty with Energy For All, which would keep everyone warm this winter."