Labour has promised to boost the benefits of the "unsung heroes" who care for the vulnerable by £10 a week if the party wins the next election.
During a visit to Birmingham on Tuesday, Jeremy Corbyn is expected to say a 17% increase in Carer's Allowance would help around one million people in the first year of a Labour government.
Under the plan, Carer's Allowance would rise from £62.70 to £73.10 a week.
Ministers say they will spend an extra £2bn on social care over three years.
Carer's Allowance is paid to around 6.5m people in the UK who care for older, disabled and seriously ill friends or relatives for at least 35 hours a week.
Eligible carers cannot earn more than £116 a week after tax.
Mr Corbyn said he believed it "would be a good thing to do" to help carers, "usually women" who have to give up their jobs to look after elderly relatives at home.
"Caring for people is stressful," he told the BBC. "In some way it's enjoyable because you want to do it, but you shouldn't be impoverished because of it. It's also lonely."
In his speech later, the Labour leader will claim "Britain's social care crisis was made in Downing Street by cutting £4.6bn from council care budgets".
"Millions of unpaid carers have been forced to fill the gap and put under even greater pressure as a result," he will say.
"The care they give to the disabled, sick and elderly saves taxpayers £132bn a year. So we believe these unsung, unpaid heroes not only deserve our praise and recognition - they deserve better financial support.
"That's why Labour is convinced it's both morally and economically right to give the Carer's Allowance a boost of £10 a week.
"We also think it's only fair that this extra support for carers is funded by scrapping the Tory cut on inheritance tax, which will only benefit the wealthiest people in Britain.
"This will be the first step in helping to transform our social care system for the 21st century and boosting support for family carers."
According to Labour, up-rating Carer's Allowance would cost £538m by 2020/21. This would be covered by scrapping the expected £650m cut to inheritance tax, which allows married couples to pass on estates worth £1m free of death duties.
But the Conservatives claim Labour would be unable to fund the promise to increase the allowance.
Luke Hall, a Tory member of the Commons work and pensions select committee, said: "Carers make a huge contribution to society, so it's only right that we do everything we can to support the selfless work they do.
"That's why we already increased the rate of Carer's Allowance, meaning an additional £450 a year for carers since 2010.
"Labour have already committed the money from corporation tax cuts 11 times over, so there is no way they could find the additional money for this promise.
"It's not worth the paper it's written on - just like Labour's reputation for economic management."
The government has recently committed to spending an extra £2bn on the social care system over the next three years and allowed local authorities to raise council tax bills in order to fund social care services.