A backlog of care claims is expected to cost the NHS £250m this financial year.
They were made under the Continuing Healthcare scheme, which funds the care of those with complex health needs outside a hospital setting.
The health ombudsman says there are 40,000 outstanding cases, with some having waited years for a decision.
NHS England said £250m additional funding had been made available for this financial year (2014-15) and £30m had been spent so far.
Five years ago Chris Andrews, from Gillingham, sold his parent's house to pay for them to be looked after in a nursing home after they began suffering with dementia and other health problems that left them in need of 24-hour care.
'Money's running out'
He knew nothing about Continuing Healthcare or the fact that his parents might have qualified for it at the time but has since put in a retrospective claim for funding.
He has been waiting two and a half years for a decision on that retrospective claim and says he is now worried his parent's own money may run out before he gets a decision.
Mr Andrews said: "My mum has reached a stage now, she can't even express what she wants, she can no longer speak.
"How far has this got to go before funding is in place? Mum and Dad have now spent over £240,000. Money is running out quick now."
Parliamentary and Health Ombudsman Julie Mellor said: "Some people have waited two years already, and there seems to be no timetable on when people will be assessed. That is unfair to claimants.
"My big concern is that there are 40,000 cases waiting for reviews by clinical commissioning groups. I would like to see those cases being reviewed as a matter of urgency."
A spokeswoman for Medway Clinical Commissioning group said Mr Andrews's was one of 227 backlog cases it had inherited from the local primary care trust, which was abolished when clinical commissioning groups were introduced following health reforms last year.
She said: "We understand the frustrations for patients whose cases are held up in this backlog and are working diligently to ensure it is cleared as soon as possible."
Dr Steve Kell co-chairman of NHS Clinical Commissioners, the body which represents clinical commissioning groups (CCGs), said Continuing Healthcare claims were one of a number of competing pressures on budgets.
He said: "CCGs are still new organisations and need support and adequate resources to be able to manage the Continuing Healthcare process - the current state of which is not of their making - with some claims going back as far as 2004."
An NHS England spokeswoman told BBC Radio 4's File on 4 programme: "We are confident we have the funds in place to resolve any legacy issues around Continuing Healthcare funding. File on 4 is right to highlight the challenge the NHS faces in meeting the needs of an ageing population."