Nursing homes will close and support for elderly and disabled people will be put at risk without extra cash to tackle a social care funding crisis, leaders in the sector have warned.
George Osborne said social care could expect a cash boost through local authorities raising their council tax, as part of his Spending Review last month.
But the Care and Support Alliance (CSA) claims there is likely to be a real-terms cut in their funding and have called for urgent talks with the Chancellor.
In a letter to Mr Osborne, the Association of Directors of Adult Social Services (Adass), the Care Provider Alliance, the Care and Support Alliance and the NHS Confederation, warn the spending settlement "is not sufficient to resolve the care funding crisis".
"Ultimately the package put forward for social care will not enable us to fill the current gap in funding, cover additional costs associated with the introduction of the National Living Wage, nor fully meet future growth in demand due to our ageing population," it adds.
The organisations warn that more older and disabled people face being left without the care they need, more care homes will close down and the NHS will come under increasing pressure from admissions.
After the Spending Review, the Institute for Fiscal Studies think-tank warned that due to cuts of more than 50% in central government support over the five-year period for councils in England, their spending power will be more dependent on their ability to raise tax locally.
The Chancellor told MPs last month that £2 billion could be raised if all councils added 2% to council tax, and the money would be spent on adult social care.
He also said the Better Care Fund - which oversees integration between the NHS and social care - would have an extra £1.5 billion by 2019-20 for local authorities to access.
Adass president Ray James said councils could struggle to put more money into services, leading to a direct effect on their ability to provide care.
He told the BBC: "Councils have tried to prioritise funding for social care ahead of other services. But its ability to do that seems to have come to an end, so I think we will struggle to put much more into social care.
"If that happens, services will be put at risk. We have an ageing population which is increasing demand and have to cope with the introduction of the National Living Wage.
"Without action, we will see care homes close and vulnerable people not getting care."
Vicky McDermott, chairwoman of the CSA, told BBC Breakfast: "There is just not enough money and it's not being funded quickly enough, so actually what we're likely to see next year is a real-terms cut in funding for those vulnerable people."
A Department for Communities and Local Government spokesman said: "The social care precept is part of a wider £3.5 billion investment package to ensure councils can support older and vulnerable people in their area.
"In particular, the increased and improved Better Care Fund will offer support to councils with greater demands for their social care services, on top of the funds they raise through the precept.
"This comes as councils will have almost £200 billion to spend on local services over the lifetime of this Parliament - a cash-terms increase and a reduction of just 1.7% in real terms each year."