Care services are facing cuts this year as rises in council tax have failed to plug the gaps in budgets in England, town hall chiefs are warning.
The government allowed councils to increase council tax by 2% this year to spend on care - and most have done so.
But, according to a survey of all 151 social care directors, there is still a shortfall of nearly £1bn.
The Association of Directors of Adult Social Services said councils had no option but to reduce the services.
Directors in charge of care for older people and adults with disabilities indicated in the annual survey only about half of this shortfall could be met by efficiency savings.
Council tax 'can rise to fund care'
How the systems differ in the UK
Instead, they said, 39% of the shortfall would have to be covered by cuts to services, with those provided to the elderly most at risk.
This could lead to day centres being closed, fewer hours of help being provided in people's homes and an increase in rationing resulting in a cut in the number of people actually getting services, the ADASS said.
The rest of the savings will be met by other measures, such as increasing the fees people are charged - unlike with NHS services, people can be asked to make a contribution to the care they get.
ADASS president Harold Bodmer said: "We have been arguing for some time that adult social care needs to be given the same protection and investment as the NHS. Services are already being cut, and the outlook for future care is bleak.
"We are at a tipping point where social care is in jeopardy."