Social care provision should be modelled on the state pension, with taxpayers funding a flat-rate “universal care entitlement”, which patients could supplement from their own funds, according to former Conservative cabinet minister Damian Green.

In a report published by free market thinktank the Centre for Policy Studies, Green argues that current social care provision is patchy and inadequate, and the government should be spending an additional £2.5bn on it each year.

In order to fund the more generous state provision, Green suggests taxing the winter fuel allowance and redirecting any savings made in the forthcoming spending review.

As a “last resort”, he says, the over-50s might be asked to pay a 1% national insurance surcharge, “in exchange for a guarantee that their personal finances will not be exhausted by the costs of social care, and that they will be looked after whatever their condition”.

Green said the proposals would “put social care on a solid footing in this country”, and would model the state pension system in being simple to grasp and fair.

Labour immediately seized on the proposal for a national insurance surcharge, with the shadow chancellor, John McDonnell, calling it “a tax on getting old”.

“After nearly a decade of brutal cuts to social care, the Tories now want to make older people pay through increased taxes.

“We want to hear today a clear statement from the government that they will reject this call, protect the triple lock, and follow Labour’s call to fund social care properly,” he said.

However, Green argued the funding boost would allow Whitehall to provide a universal, flat-rate entitlement, of perhaps £2,000 a month for residential care, or £2,500 a month for nursing care for example.

Q&A What is the social care green paper? Show The much-anticipated green paper on social care for older people is due to be published in the autumn of 2018. The government originally promised the green paper before last year's general election, but then said it would be unveiled before MPs' summer recess – although there were hopes it would appear much sooner. It was also hoped the paper would address needs across the entire adult social care sector. Instead, the paper will be limited to the government’s plans for improving care and support for older people and tackling the challenges presented by an ageing population. There will be a "parallel work stream" on working age disabled adults, but some are concerned this report will focus on getting more disabled people into work. The government has invited a number of people to advise on the paper, including Paul Burstow, chair of the Social Care Institute for Excellence; and Caroline Abrahams, charity director of Age UK. However, no user or care worker representatives have been invited. During a cabinet reshuffle in early January, Jeremy Hunt became secretary of state for health and social care. Despite already having social care in his mandate, the change gave Hunt lead responsibility for the green paper. The proposals set out in the paper will build on the additional £2bn the government has provided to meet social care needs, reduce pressures on NHS services and stabilise the social care provider market over the next three years. Once published, the paper will be subject to a full public consultation.

He suggested the funds could be paid directly by government to an approved care home chosen by the patient and their family, after a needs assessment by the local authority.

Under the plans, some patients could also buy an insurance-style “care supplement”, to fund a higher standard of provision, perhaps by releasing part of the value of their property.

Green said social care had to be moved to a national level, rather than being the responsibility of councils.

“You look ahead at the demographics – there are going to be twice as many over-75s in 40 years than there are now, 10 million rather than 5 million,” he told BBC Radio 4’s Today programme.

“That means that means that almost all local authority budgets, at the way we’re going, will be sucked into paying for social care, which won’t leave money for anything else.”

Green said it was fair to ask older people to pay rather than all citizens: “Given you have this huge raft of wealth, particularly in housing, £1.6 trillion that people have in housing wealth – a sliver of that, frankly, used for social care would buy peace of mind in your old age and would get more money in the social care system.”

Social care funding has become an increasingly toxic political issue. Campaign group Age UK estimates that total public spending on social care has declined by £160m over the last five years despite rising demand; and 1.2 million of over-65s are missing out on the help they need.

The chancellor has repeatedly been forced to set aside extra funding to relieve the intense short-term pressures on local authorities, which have responsibility for meeting patients’ needs.

But the government has repeatedly delayed publishing a long-promised green paper on a new long-term funding model, fearing a backlash such as that following the announcement in the party’s 2017 general election manifesto of what became known as the “dementia tax”.

Theresa May’s insistence that “nothing has changed”, after the Conservatives hastily announced that there would be a cap on care costs, became one of the defining moments of a disastrous campaign.

After the election, Green, who was then work and pensions secretary, was initially meant to be overseeing the green paper, and his intervention is being awaited with interest in government.

A close ally of May for many years, he was sacked as first secretary of state in December 2017, after admitting he lied about the presence of pornographic images on his House of Commons computer, following an investigation into a complaint of sexual harassment.

A Department for Health spokesperson said the green paper on social care would be published “at the earliest opportunity”.