Sir Andrew Dilnot, who led a review into the future of funding social care a decade ago, said those with less assets “will not see any benefit”, with the Government set to make savings “exclusively” from this group.
Sir Andrew said he is “very disappointed” that only people’s personal contributions will count towards the £86,000 cap.
In a policy paper uploaded on Wednesday, the Government said this is to ensure people “do not reach the cap at an artificially faster rate than what they contribute”.
But Sir Andrew said there is a “sort of North-South axis to this that people living in northern and other less high house price areas are likely to be hit harder by this on average”.
He said poorer people with long care journeys will end up paying as much as their better off counterparts, and for some the amount of time they spend paying contributions towards their care could double.
In 2011, a commission headed by Sir Andrew recommended capping the amount someone should pay for care in their lifetime, fixed at between £25,000 and £50,000.
The Government is proposing a lifetime cap of £86,000 from October 2023, with people with assets less than £20,000 paying nothing and those with up to £100,000 contributing to their care.
It is funding the reforms through a tax rise known as the Health and Social Care Levy.
Sir Andrew said it should be “noted and welcomed” that the proposals will move the system away from a total reliance on means testing to a national risk pool for social care.
He gave credit to the Government for having the “courage” to deliver the proposals, but said parts – particularly the detail which emerged on Wednesday – make him “very uncomfortable”.
He told the Treasury Select Committee on Thursday: “The change that the Government proposes, about which I am very disappointed, is that rather than doing it as we had suggested, the metering towards the cap would be of accumulated need minus any means tested support that the Government delivers.
“And that means that my less well-off doppelganger would hit the cap significantly later in time and having spent exactly the same money as me, his better off peer.”
For those who have long care journeys and significant care needs, the change means the “less well-off will not gain any benefit from the cap”, he said.
The Government plans to amend the Care Act to ensure the reforms are clear, subject to parliamentary approval.
Asked how much he thinks the change could save, Sir Andrew estimated it could be hundreds of millions a year, but less than a billion.
He added: “I think it’s disappointing, it finds savings exclusively from the less well-off group.”
Boris Johnson dismissed the suggestion that the plans would disadvantage people in the North of England.
Asked during a visit to a Network Rail logistics hub near Selby, North Yorkshire, the Prime Minister told reporters: “No. This is a massive improvement for everybody in the whole country because what we’re saying is for the first time in history, we’re stopping people having to pay unlimited quantities for their care.”
Sir Andrew said people with significant care needs and assets of £106,000 will be hardest hit by the changes to the cap, but it will not make a difference to anyone with more than £186,000.
He said around 60% of older people who end up needing social care have assets less than £186,000 and about 30-40% less than £106,000.
A “very large proportion” of older people – tens of thousands – will find themselves “materially less protected”, he said, adding: “Those people with less valuable houses but facing significant care journeys, they would be much less protected against catastrophic risk and the sale of their house if this amendment is made than without it.”
Liz Kendall Labour’s shadow social care minister, called the cap a “con”, adding that “ordinary working people are facing a tax hike that will do nothing to improve care now, and instead of protecting their parents’ homes, will only protect the homes of the wealthiest in our society”.
Mark Jackson, Marie Curie policy manager for England, said: “Everybody deserves the best possible care at the end of life – not just a privileged few.”
He added that the system needs real reform, not just funding changes “that will hit the worst-off hardest”.