Map shows areas that would be worst hit by a cut to benefits

Liz Truss is facing increasing pressure from her own ranks to raise benefit payments in line with inflation instead of earnings growth.

The prime minister is reported to be planning to use the latter measure, which would mean an increase of around 6% instead of 10%.

If this goes ahead, nine million UK households containing 30 million people will lose out from the real-terms cut, warns the Resolution Foundation think-tank.

Truss’ predecessor Boris Johnson pledged to raise benefits in line with inflation, but the new PM has made no such commitment.

It comes as her government is already under fire over its recent mini-budget, which included a £45bn raft of tax cuts – funded by public borrowing and mainly benefiting the wealthy.

Many now fear that refusing to raise benefits in line with inflation will spark a civil war within the party, with backbenchers, peers, and some of Truss’ own ministers urging her to reconsider.

Analysis by the Joseph Rowntree Foundation (JRF) has revealed the impact of a real-terms benefit cut in each of the UK's parliamentary constituencies by calculating how many working-age families receive benefits that would be affected by the uprating decision.

In Hodge Hill Birmingham, 61% of working-age families receive means-tested benefits and could see their incomes fall.

In Bradford East, Bradford West, Birmingham Hodge Hill, Belfast North and Belfast West more than 50% of working-age families claim relevant benefits and would see a drop in their incomes.

Scroll to the bottom of the article to see the 20 areas with the highest proportion of working-age families receiving affected benefits

The JRF found nearly 200 Tory MPs would see more than a fifth of families in their constituencies suffer real-terms benefits cuts.

Two thirds of MPs represent areas where at least 20% of working-age families receive means-tested benefits, including 193 Tories.

The prime minister’s South West Norfolk constituency would see 21% of working-age families facing cuts.

The cut would affect seats currently held by 180 Labour MPs and 34 from the SNP, according to the research.

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The charity’s principal policy adviser, Katie Schmuecker, said: “Politicians should think long and hard about the impact of withholding hundreds of pounds from thousands of families in their constituencies when the basic rate of benefits is already at its lowest in real terms for 40 years and prices are sky-high.

“It is unconscionable that the government should be considering cutting their ability to pay for what they need.

“The government must realise how catastrophic it would be to refuse to respect their own party’s pledge to make sure the value of benefits keeps up with prices.”

According to the Resolution Foundation, seven million of the nine million affected households already contain someone who is working.

Rampant inflation, soaring energy costs and stagnant wage growth mean these families still rely on benefits from the state to make ends meet.

The think-tank said an uprating of benefits by earnings would set the typical incomes of the poorest fifth of households back to levels not seen since 2000-01.

This would represent an “unprecedented period of living standards stagnation” for millions of the poorest families, it said.

Chancellor Kwasi Kwarteng will announce the government’s decision during his medium-term fiscal plan on 31 October.

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The Resolution Foundation analysis, The Long Squeeze, estimates uprating benefits in line with the recent earnings growth – 5.5% – would save the Treasury £3bn by 2026-27.

Certain benefits must be increased in line with rising prices, including personal independence payment, attendance allowance, disability living allowance, carer’s allowance and incapacity benefit.

Working parents who receive universal credit and child benefit would be hit the hardest by a real-terms cut and would be set to lose almost £1,000 a year, the Resolution Foundation said.

A working single parent with one child would lose £478, and a working couple with three children would lose £978.

A couple with one child only receiving child benefit would lose £52 a year, while a single disabled adult on universal credit would lose £380.

Overall, some three million households are set to lose more than £500, the foundation added.

The 20 constituencies with the highest proportion of working-age families claiming benefits affected by the uprating decision

Hodge Hill Birmingham, West Midlands, 61%

Bradford West, Yorkshire and The Humber, 57%

Belfast West, Northern Ireland, 56%

Bradford East, Yorkshire and The Humber, 51%

Belfast North, Northern Ireland, 50%

Walton Liverpool, North West, 49%

Hall Green Birmingham, West Midlands, 48%

Perry Barr Birmingham, West Midlands, 48%

Blackburn, North West, 48%

Blackley and Broughton, North West, 48%

Foyle, Northern Ireland, 47%

Blackpool South, North West, 46%

East Ham, London, 46%

Edmonton, London, 46%

Gorton Manchester, North West, 45%

Middlesbrough, North East, 45%

Oldham West and Royton, North West, 45%

Tottenham, London, 45%

Yardley Birmingham, West Midlands, 44%

Erdington Birmingham, West Midlands, 43%