By Nick Triggle
Health reporter, BBC News
Care funding is currently means-tested
The number of people being excluded from social care in England will continue rising unless there is a major revamp of the system, experts warn.
The King's Fund think-tank pointed out rationing had already started with many councils only helping the most in need.
It said the best way to limit the problems was to create a partnership between the state and individuals where both contributed to the cost of care.
It comes as ministers are discussing changes to the funding system.
Home help and residential care for the elderly and adults with disability is currently means-tested so that those with assets of more than £23,000 do not get state support.
WHERE THE PARTIES STAND
Labour - Put forward three proposals - all of which involve the state providing a basic level of care which would be topped up by either personal contributions, a voluntary insurance scheme or compulsory levy. The third option - dubbed a death tax - is said to be favoured by ministers
Tories - Proposed an £8,000 voluntary insurance model to cover residential care costs. Now drawing up plans for a voluntary scheme to cover domestic care, such as help washing, eating and dressing in the home
Lib Dems - Initially supportive of free personal care - like Scotland has introduced - but now want a "partnership" whereby state pays some and individual tops this up. Open to compulsory levy
But the increasing demands on councils because of the ageing population have led them to place even tighter restrictions so that only those with the most severe problems get help.
It means the numbers being supported have actually fallen slightly in the past four years despite a 5% rise in the number of over-75s.
The King's Fund last looked at the social care system in 2006.
The report, led by former government adviser Sir Derek Wanless, proposed what was then considered a radical shake-up of the system.
It suggested a partnership between the government and individuals whereby the state would meet at least two-thirds of the cost of care.
This report updates that by looking at the latest data on the ageing population and the state of the public sector finances.
It has revised the state contribution down saying it should only meet 50% of the costs.
This model of care would allow about 1.8 million people to get access to care by 2026 - 700,000 more than the current system would - because councils would be able to afford to provide help to those with less severe needs.
However, despite the partnership model bringing in billions of pounds a year in personal contributions, the cost to the state would still rise to £15.5bn by 2026.
The King's Fund said this would make it more expensive than leaving the status quo in place.
But Anna Dixon, acting chief executive of the think-tank, suggested it was a price worth paying.
"The current social care system often falls short of meeting the needs of the people who rely on it and will not be able to cope with increasing demand for services as the population ages.
"The people who stand to benefit most from our proposals are those on moderate and middle incomes who are heavily penalised by the current system."
The government said it would be publishing its own plan soon.
Last summer it set out three options - one of which was also a form of partnership, albeit where the state provided a smaller proportion of funding than the King's Fund has put forward.
Councillor David Rogers, of the Local Government Association, said: "We cannot wait any longer to fix the system which provides adult social care.
"The combination of insufficient funding, increased demand from an ageing society and escalating costs is already placing an immeasurable strain on services."