Larger families will “miss out” on some of the chancellor’s support for soaring energy bills, the Resolution Foundation has said.

Mike Brewer, chief economist at the think tank, said the decision to use one-off payments means single adults on benefits or in receipt of a state pension will see a bigger advantage from the £650 they will get through the plans.

Among benefit claimants, families with more than three children will pay £500 more for energy bills than single people, he said.

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“Regardless of whether you are a single young person on Universal Credit, or whether you are, say a family with three or four children, you still just get that £650,” he told Sky News.

“But of course, we know that larger families are going to live in larger houses, their energy bills are much higher, and their energy bills are going up by much more.”

Torsten Bell, chief executive of the think tank, said Mr Sunak has “gone big and targeted support in the right place – but larger families will miss out”.

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The Resolution Foundation pointed out that families with three or more children are especially badly affected by growing energy bills – 13.6% of them would have been in severe fuel stress this winter without the chancellor’s new cost of living support package.

The think tank welcomed the increase in benefits so that they would be in line with October’s inflation rate, but said that because this will not take effect until next April, larger families will receive £113 less than they would have if this were implemented in the autumn.

The chancellor’s cost of living package includes £650 for eight million of the lowest-income households, £300 for pensioners who get winter fuel payments, £150 extra for those on disability benefits, and £400 for all households.

The Institute for Public Policy Research, another think tank, welcomed the “overdue” steps to help the poorest families with the cost of living crisis, but said more is needed – including making the temporary measures permanent to reflect continuing expected rising prices over the next two years.

Rachel Statham, IPPR associate director for work and the welfare state, said: “Is the support offered a sticking plaster or a safety net? This is a living standards crisis of historic proportions – and those on the lowest incomes are most exposed.

“We need to see support that can keep families afloat not just this year, but into the future.

“Today’s measures offer temporary relief, but any long-term solution must ensure our social safety net is fit for purpose.”

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