This week ministers are set to agree in principle a cap on what people in England pay towards their own care.
But Labour says the plans are “meaningless” without more details and a timetable.
And Michelle Martin, director general of Age UK said the government’s plans were “not nearly enough”.
“The government must set out the process by which it will make the all-important decisions about funding social care, including timescales and milestones,” she said.
“That is the very least older people and their families will be looking for next week.”
Acceptance of the recommendations would be “a step forward and welcome” she added.
Health Secretary Andrew Lansley has said that legislation to change the funding of social care for elderly and disabled people in England could be introduced during this Parliament.
Last July, a review chaired by economist Andrew Dilnot put forward a raft of ideas for changes to adult social care funding in England.
Chief among these was a £35,000 cap on what people should pay towards home visits or care home costs before they get help from the state.
But shadow health secretary Andy Burnham said: “A cap is meaningless if there is no plan to deliver it. How is it going to be paid for? What is the timetable to put it in place?”
Care Minister Paul Burstow said Labour had failed to make changes to the care system when it was in office, and that the coalition government would “spell out in detail how we will change the system to comprehensively reform it for the 21st Century”.
The Care & Support Alliance says one in two people needs care in their lifetime costing more than £20,000, while one in 10 requires care costing upwards of £100,000.
Chairman Simon Gillespie said: “We need to make sure that we have got arrangements in place so that that risk can be shared.
“People understand that it’s got to be a shared contribution between the overall taxpayer but also individuals as well.”
Disability charity Scope said disabled people, who make up a third of the people who rely on social care, “desperately need clarity”.
Chief executive Richard Hawkes said: “A year on from Dilnot they are still waiting anxiously for the government’s plan.”
Campaign groups have also said they fear the plans will be shelved because of the cost.
Currently in England, council-funded home help and care home places for the elderly and adults with disabilities are offered only to those with under £23,250 of assets.
The Dilnot report said the assets threshold should rise to £100,000 and a £35,000 lifetime cap on costs would be “fair”.
Just over £14bn a year is spent by councils on social care and changes would cost an extra £1.7bn a year if they were implemented now. This figure could rise by 50% as the “baby boom” generation begins to retire.
BBC political correspondent Robin Brant said the government will sign up to the funding cap principle when it publishes its White Paper on Wednesday, but ministers will not make any pledges on specific figures because there is no agreement yet on how to pay for it.
With the UK economy showing little sign of recovery and the coalition still not halfway through its deficit reduction plan, the chancellor wants to delay a decision until at least autumn next year in the government-wide spending review, our correspondent adds.
Labour claims there have not been any substantial talks on the issue since February and wants publication of next week’s proposals postponed.
Scotland offers free nursing care to all those at home, and will contribute towards costs for those living in a care home.
Wales and Northern Ireland are waiting to see what happens in England following the Dilnot conclusions.
Published by BBC News 7 July 2012 Last updated at 16:37 See http://www.bbc.co.uk/news/uk-politics-18754431