The Green Party has pledged to raise taxes on top earners in its manifesto, claiming the plans will generate £70bn a year to mend “broken Britain”.

The plans include raising the National Insurance (NI) rate to 8% on annual wages above £50,270 – equivalent to an extra £283.74 per year in tax for someone earning £55,000.

They will also introduce a wealth tax of 1% on assets worth over £10m, and 2% on assets worth more than £1bn.

Party co-leader Adrian Ramsay said the Greens were the “only party being honest” about the scale of changes needed to fix the climate crisis, housing and the NHS​.

The party pledged to invest tens of billions of pounds in public services and stop all new fossil fuel projects in the UK.

Mr Ramsay said the Greens were not expecting to form the next government but their MPs will be in Parliament to “speak up for you on the issues you care about”. The party will focus their efforts on four seats they see as winnable.

At the manifesto launch in Hove, co-leaders Carla Denyer and Adam Ramsay said electing Green MPs would “push Labour to be bolder”, particularly on Net Zero climate change policies, which they accused other parties of “running away from”.

“Most people are working harder and yet getting poorer,” Ms Denyer told supporters, but “transforming” tax would “end the rip-off of rising bills, appalling services and shareholders trousering millions”.

Conservatives and Labour have been holding “a race to the bottom” on lowering tax, she said, by taking “2p off here and a penny off there”.

“They think people won’t cotton on that this means even more devastating cuts to public services like the NHS that we rely on every day,” she added.

The Greens say the new wealth tax would affect fewer than 1% of UK households and raise £15bn a year by the end of the next Parliament, with the money going to the NHS.

The party has committed to spend £50bn per year on health and social care by 2030.

Mr Ramsay said the increase was “modest” by European standards. He said a small number of millionaires may leave the UK as a result but insisted the super rich would stay.

Currently employees pay no National Insurance until they earn more than £12,570, 8% on earnings of between £12,570 and £50,270, and 2% on earnings of above £50,270 for the 2023/24 tax year.

Under the Greens’ plans, the 8% rate would be paid on all wages above the upper earnings threshold.

On taxes, the Greens have also said they would:

• Have no further increases on the main rates of corporation tax
• Introduce a carbon tax on businesses starting at £120 per tonne emitted, rising to £500 per tonne over 10 years, to push businesses to decarbonise
• Expand the 75% windfall tax on fossil fuel profits to banks, aiming to raise an extra £9bn a year
• Bring Capital Gains Tax in line with income tax bands.

Arun Advani, a wealth expert from the University of Warwick said raising this much through a wealth tax was credible, depending on the design.

However, Institute for Fiscal Studies deputy director Helen Miller said the Greens were unlikely to raise as much revenue as expected.

“Overall borrowing would end up around £80 billion a year higher,” she said, adding a recurrent wealth tax would be tough to implement and “would hit a lot of workers on not terribly high salaries – many nurses and teachers for example.”

Among its proposals, the party set out plans to tackle the housing crisis and make homes warmer and cheaper to run by increasing energy efficiency.

Sian Berry, who is the party’s candidate for the Brighton Pavilion constituency, said her passion was to get a fair deal for tenants “so that renters don’t have to live at someone else’s mercy”.

The “rental rollercoaster” is “destroying lives” and bringing in rent controls, stabilising tenancies and ending no-fault evictions was “not a pipe dream”, she said.

“Greens are proud of our policy to help end the crisis in rented housing by introducing rent controls.

“Decided locally and based on what the housing market looks like in the local community, this would allow all of us to make sure rents are affordable and stay connected with local earnings.”

On transport, the Greens say aviation is the fastest-growing source of CO2 emissions, and claim “it’s the wealthiest driving this trend”.

They plan to ban all on domestic flights for journeys that would take less than three hours by train.

They also want to stop airport expansions and introduce a frequent-flyer levy.

Other key policies include:

• Supporting the switch to electric vehicles
• Guaranteeing access to an NHS dentist
• Investing in public transport and bringing railways into public ownership

The Greens plan to field candidates in every constituency in England and Wales for the 4 July election. The Scottish Greens are a separate party.

Mr Ramsay also confirmed four out of 574 candidates have been replaced after the party launched an investigation into reports of antisemitic or extreme comments.

He said: “Out of that huge number, there were four who were originally selected who are now not going forward and have had new candidates put in their place.”

When pressed over other candidates who had been investigated, he said: “I can’t recite every candidate” adding that the process is “separate from the leadership as a matter of good governance”.