People in Cornwall spent tens of millions of pounds of their own money to care for friends and relatives last year, new figures show.
Spending for adult social care has rocketed across England, but health think tank the Nuffield Trust warned patchy data means the amount paid privately is likely underestimated.
Chancellor Jeremy Hunt announced a further £4.7 billion in funding for adult social care up to 2024-25 in last year's autumn budget, but the Local Government Association wrote to him ahead of this year's budget calling for "substantial new investment to help tackle unmet and under-met" needs.
NHS Digital figures show people in Cornwall paid £29.2 million for adult social care services in 2022-23 – though this was down from £29.6 million the year before.
In total, Cornwall council spent £339 million providing services last year.
It can offset the amount it spends on providing care through various income and funding streams, such as investment from the NHS and contributions from patients.
Last year, it received £81.1 million. It means the council's net spend on providing adult social care sat at £258 million – up from £251 million in 2021-22.
The LGA wrote to Mr Hunt last week, urging him to provide further funding for councils to deliver adult social care services. It said last year's investment "will do little more than allow councils to stand still".
Cllr David Fothergill, chairman of the LGA's Community Wellbeing Board, said: "Councils have increased their spending on adult social care, but evidence shows that there is still an unacceptable amount of unmet and under-met need.
"Councils are facing increased demand for services and unprecedented inflationary and pay pressures, and urgent action must be taken to address these issues."
Further NHS Digital figures show 3.2% of people were extremely or very dissatisfied with the level of care they received last year – one of the highest proportions in the country.
Meanwhile, 65.9% were extremely or very satisfied with their care.
Natasha Curry, deputy director of policy at the Nuffield Trust, said: "Means testing thresholds haven't changed since 2010, so fewer people qualify for public funding, and those who pay for their own care are finding it to be more expensive due to inflation.
"Many self-funders are forced to make the difficult decision to reduce the care visits and packages that they access because costs are too high."
A Department of Health and Social Care spokesperson said: “The Government has made available up to £8.1 billion over this year and next to strengthen adult social care provision. This funding will enable local authorities to buy more care packages, help people leave hospital on time, improve workforce recruitment and retention, and reduce waiting times for care.
"The new funding represents a more than real terms increase and data published last week showed that spending on adult social care has increased in real terms for eight consecutive years."