A minimum of £3.4 billion will be required to meet the growing need for social care, according to new analysis.
The Health Foundation think tank said the funding would be required by 2028/29 to avoid a further deterioration in the sector.
It called on the Government to “signal its commitment” ahead of the upcoming spending review with a “down payment on the investment needed for reform”.
It comes as nurses warned of a “time bomb” in social care.
According to the Health Foundation, £3.4 billion is the minimum amount needed to cover rising costs to employers by 2028/29.
The analysis claims this could rise to £9.1 billion by 2034/35.
Elsewhere, the think tank claims £6.4 billion would be required to cover rising costs and improve access to care by 2028/29, rising to £12.7 billion by 2034/35.
Some £8.7 billion would help meet demand, cover rising costs, improve access and boost pay by 2028/29, rising to £15.4 billion by 2034/35.
Hugh Alderwick, director of policy at the Health Foundation, said: “The fiscal outlook means tough decisions for the Chancellor at the forthcoming spending review.
“Decades of political neglect mean the social care system is a threadbare safety-net, with too many people falling through the gaps.
“The spending review is a chance for the Government to signal its commitment to improving social care by providing a down payment on the investment needed for reform. This would help people get the support they need, ease the burden on unpaid carers, provide a fair wage to care workers and support the NHS.”
The analysis comes days after the formal launch of the Casey Commission, which will aim to transform social care.
The first phase of the review is expected to report next year, although recommendations from the initial probe will be implemented in phases over the course of 10 years.
Social care leaders have raised concerns over the potential timeline of 2036 for some reforms to be introduced.
The second phase of the commission, setting out longer-term reforms, is due to report by 2028.
Mr Alderwick added: “The Casey Commission aims to set out a plan for social care reform, but the Government’s timeline for the commission risks more fundamental changes being ducked or delayed, despite problems in the sector being well known, so we encourage the commission to bring forward proposals for reform as soon as possible.”
On Wednesday, nurses also demanded that UK governments take action to invest in social care.
Speaking at the Royal College of Nursing’s annual congress in Liverpool, BJ Waltho, of the union’s Dorset branch, said: “Investment in social care in the UK is needed to address the demands and workforce shortages.
“Introducing new immigration rules by ending the recruitment of care workers from overseas is not the answer.”
Ms Waltho urged Prime Minister Sir Keir Starmer to “act today”, adding: “I know the governments are saying that money is tight, but investing money in social care is value for money, better for patients and better for society.
“This is a time bomb.”
Responding to the Health Foundation’s analysis, RCN director for England, Patricia Marquis, said: “This report is further evidence of the scale and urgency of the challenge in social care.
“As the needs of vulnerable people go unmet and nurse vacancies continue to rise, we need action and ambitious investment.
“At the very least new funding to match demand and improved pay at least in line with that of the NHS is needed to stabilise the domestic workforce, especially with ministers closing the care worker visa route.
“The fair pay agreement can be a crucial step forward but that cannot wait forever either. Staff and the sector need certainty.”
A Department of Health and Social Care spokesperson said: “This Government inherited a social care system facing significant challenges, but we are turning this around through our Plan for Change, building a National Care Service that is fair and affordable for all.
“This analysis does not reflect the extra £3.7 billion we have made available this year to improve services.
“Baroness Casey has started her work on the independent commission into adult social care to build cross-party consensus and will publish her first recommendations for reform next year.”
