Audit Scotland found councils and NHS boards have to improve the way they commission and deliver services, which range from basic personal care needs to mental health problems and serious illness.
Auditors also said a greater understanding was needed among councils and health boards to cope with a shift to self-directed support, which aimed to give people a greater say in the services they received.
John Baillie, chairman of scrutiny body the Accounts Commission, said: “Social care in Scotland faces a number of challenges. As budgets come under growing pressure, there are signs that councils are concentrating resources on people who need intensive support.”
The report, called Commissioning Social Care, found that councils and NHS boards do not have sufficient information to make informed decisions to spend resources.
An ageing population is putting pressure on budgets, which will have to cope with a 147 per cent increase in the number of people aged 85 and over in the next 25 years.
A Scottish Government spokesman said: “We recognise that we must always strive to continually improve the delivery of care and that we need to make better use of the resources we commit to health and social care in Scotland.”