The pro-independence Yes Scotland group will attempt to capitalise on opposition to Conservative-led austerity measures with a weekend of campaigning as a new report shows the basic cost of living has soared by 25% since the economic slump began in 2008.

According to social policy think-tank the Joseph Rowntree Foundation (JRF) families are facing an "unprecedented erosion of household living standards" because of rising inflation and flatlining wages.

The report concludes that for the first time in more than 80 years people voting at the next General Election are likely to have a lower standard of living than those who voted at the last one.

About half a million leaflets will be distributed by Yes Scotland in an attempt to highlight what policies Scotland has opposed but Westminster has pushed forward. Organisers said it is the "third key strand" of its campaign.

The group said a majority of Scottish MPs opposed the Chancellor's austerity cuts, higher VAT rate, welfare cuts and the bedroom tax.

The JRF report notes that while the Coalition has moved to take more people out of tax by raising the level of the personal allowance to £9440 in April, this has been more than cancelled out by the cuts to benefits and tax credits as well as the rising cost of essentials.

Katie Schmuecker, the foundation's policy and research manager, said: "Our research shows the spiralling cost of essentials is hurting low-income families and damaging living standards.

"The public have told us their everyday costs have soared above wage levels, driving up the amount they need to make ends meet."

Peter Kelly, chairman of the Poverty Alliance, said the report reflected the everyday pressures people in Scotland were now living with.

He added: "Combined with cuts in benefits and frozen pay for many, it is little wonder so many Scots are turning to food banks or payday lenders. Such a situation is both unacceptable and unnecessary. When the Chancellor turns the screw on those living on benefits or working in low-paid jobs he is doing nothing to help them or the economy.

"There is a need for an urgent rethink on welfare policy in the UK. But there is also a need for more to be done to help those on the lowest incomes in Scotland right now."

The inflationary pressures facing low income households are far greater than official measures suggest and explains how rising costs have implications for the earnings people now need to get by, JRF said.

In 2008, a single person earning £13,000 would have reached the minimum living standard. If their wage had risen in line with average wage increases, they would today earn £14,000 – well short of the £17,000 salary needed to cover today's higher living costs.

In 2013, to reach an adequate standard of living a single person needed to earn £16,850, a working couple with two children needed to earn £19,400 each and a lone parent needed earnings of £25,600.

The report also outlines how the cost of essentials has risen over the past five years. Childcare costs have risen over twice as fast as inflation at 37%, rent in social housing by 26%, food costs by 24%, energy costs by 39%, and public transport by 30%.

The report explains how the freeze in child benefit, the decision to uprate tax credits by just 1% and the cost of essentials rising faster than inflation means a working couple with two children will be £230 worse off a year, a working lone parent £223 a year and a single person £49 per year.

Report author Donald Hirsch, from Loughborough University, said that for the first time since the 1930s benefits were being cut in real terms by not being linked to inflation. He said: "This combined with falling real wages means the next election is likely to be the first since 1931 when living standards are lower than at the last one."

Margaret Lynch, chief executive of Citizens Advice Scotland, said the statistics came as no surprise. She added: "The CAB service in Scotland deals every day with people who are struggling to make ends meet. Many people in our society are now living in poverty, and are finding they can't rely on the welfare safety net that is supposed to support them."

The JRF research comes a week after Oxfam Scotland reported the wealthiest households in Scotland are now 273 times richer than the poorest, and the number of workers who live in poverty has risen from 255,000 to 280,000 since 2008.

Katherine Trebeck, policy and advocacy manager at Oxfam who is based in Glasgow, said: "The combination of spiralling prices – for essentials like food, fuel, housing, and childcare – alongside stagnant incomes, is pushing many people into even deeper poverty."