Only the amount that individuals directly contribute to their social care costs will count towards the lifetime cap announced as part of key reforms earlier this year, according to Government plans.

For people who receive financial support for part of their care from their local authority, only the share they contribute themselves will go towards the £86,000 cap.

This is to ensure that people “do not reach the cap at an artificially faster rate than what they contribute”, the Department of Health and Social Care (DHSC) said.

In a policy paper uploaded on Wednesday, the Government said it plans to amend the Care Act to ensure the new reforms are clear, subject to parliamentary approval.

It added that the “much more generous” means test that accompanies the cap will be the main way of helping people with fewer assets.

But groups said the change would mean such households receiving “far less protection than expected”, and that they could still face catastrophic costs that would eat up a greater share of their assets compared to wealthier recipients.

In September, the Government announced that an £86,000 cap on care costs would be put in place from October 2023.

It also said that people with assets up to £20,000 will not have to contribute anything to their care (up from £14,250), while those with assets to £100,000 will be eligible to receive some local authority support (up from £23,250).

The document published on Wednesday says local authorities will start a care account for each individual eligible for or receiving care, and will monitor their progress towards the cap.

It says: “For individuals who receive financial support for their care costs from their local authority, it is the amount that the individual contributes towards these costs that will count towards the cap, subject to parliamentary approval.”

Sally Warren, director of policy at The King’s Fund, said the change to the proposed cap has come as a “complete surprise”, just days before the proposals are to be voted on.

People with a low to moderate level of wealth will still do “marginally better” under the proposed system, she said, but the change means the proposals will no longer protect those with lower assets from catastrophic costs.

She told the PA news agency: “I think what’s coming out today is a little bit fairer than the current system for those people of low wealth, but overall, I think it’s not fair to say one person can keep 80% of their lifetime savings and be able to pass those on to their family, but somebody else could lose 90-95% of their assets.

“So I think that fairness, to me, doesn’t always mean everybody gets exactly the same.

“Fairness, to me, particularly for social care costs, would be about saying ‘you’ve got to recognise what people are starting with, as well’.”

Torsten Bell, chief executive of the Resolution Foundation, said the change will “reduce how much protection the cap provides to those with fewer assets, by making it less likely that they could benefit from the cap”.

He said: “The Government is rightly making long overdue reforms to better protect the assets of those unlucky enough to need social care support, with a more generous means test and cap on total costs.

“But the Government is now seeking to change how the means test and cap interact, leaving people with fewer assets receiving far less protection than expected.

“What sounds like a technical change will actually make a huge difference to how much families have to pay for care.

“The danger is that the cap on care costs will now offer little protection for poorer households’ assets, while doing much more for those with significant assets – especially in the south of England. We need far greater scrutiny of such a major change.”

Liz Kendall, Labour’s shadow social care minster, said poorer recipients will have to pay more as a share of their assets compared to richer people, as well as having to pay more towards the cap due to local authority contributions not counting.

She said of the “sneaked out details”: “It has now been revealed that the poorest pensioners will have to pay even more, something Andrew Dilnot – who proposed the cap – explicitly ruled out because it was so unfair.

“That this Tory Government has failed to be straight with those who’ve given so much to our country is a total disgrace, but utterly unsurprising. Our elderly people deserve better.”

The cap will also not cover daily living costs, which will be set nationally at £200 a week to cover non-care fees such as rent, food and utility bills, the Government said.

This approach “is intended to ensure a level playing field” between care home residents and people receiving care in their own home, it added.

Sir Andrew and Ms Warren will appear before a Commons select committee on Thursday morning to discuss the Government proposals.