The Action with Communities in Rural England charity (ACRE) contends the higher cost of living in the countryside means rural communities will bear the brunt of the real-terms cut in working-age state benefits.
Figures from the Office of National Statistics show weekly families in rural areas spend £50 more a week than urban households.
Meanwhile, research from rural insurer NFU Mutual shows inflation in the countryside is twice the national average.
The biggest difference is spending on transport – rural householders spend around £20 more – underlining the reliance on the car in the countryside because of the lack of public transport.
MPs this month backed a three-year squeeze on most working age welfare payments and tax credits.
By up-rating benefits by 1% – rather than pegging hand-outs to inflation – ministers will slash £5 billion from the welfare bill.
They argue the increase in benefits has far outstripped increases in wages in recent years, contending the real-terms cut is therefore fair. It is estimated almost 300,000 Westcountry households will see their benefits affected by the cap on welfare.
Benefits set to be affected by the changes include jobseeker's allowance, employment and support allowance and income support, as well as elements of working tax credits and child tax credit.
ACRE's director of policy and research Nick Chase said: "There is no doubt that these latest Government proposals are a harsh blow to those low-paid rural families who are already struggling to make ends meet.
"Countryside residents are heavily dependent on their cars due to a lack of public transport, typically having to travel twice as far to reach their nearest shops, banks and post offices as their urban neighbours.
"Rural dwellers are also hit by the comparatively high cost of heating oil, which is often used as a substitute for gas, as many rural villages are off the grid.
"We are calling on the Government to seriously consider the impact of benefit cuts on rural communities before rubber-stamping these proposals."
Cornwall's low-income economy is confirmed by the fact it is one of just two areas in the UK to get the highest level of EU state aid to revive ailing economies. But some Devon MPs say large parts of Devon are just as poor, if not poorer.
Cornwall Council Labour councillor Jude Robinson said: "What will happen is that people and families, who may have lived all their life in a village or small community, will be forced into bedsits or flats in towns miles away from their friends and relatives.
"Rural areas will be reserved for commuters and the well off. When the coalition talks about welfare reform, it is code for the usual policies that hit the poorest hardest."
ACRE, the umbrella organisation for 38 members of the nationwide Rural Community Action Network, says its in-depth studies show there are hidden pockets of deprivation in the English countryside.
Mary Creagh MP, Labour's Shadow Environment Secretary, said: "This report confirms that families in the Westcountry are set to be hit hard by the Government's tax on strivers. There are pockets of real poverty in our towns and villages where people are feeling the squeeze from rising living costs and the Government's failed economic plans. Low-paid nurses, teachers and soldiers will be badly affected by the changes to tax credits and benefits."
She added: "This out-of-touch government is engaged in a race to the bottom on rural wages by abolishing fair pay for farm workers and creating a massive growth in food poverty."
