The Green Party will demand the government introduces a wealth tax when Chancellor Rachel Reeves delivers her first budget next month.
Giving a speech at his party’s annual conference in Manchester, co-leader Adrian Ramsay said the UK “needs to invest in defending public services and protecting our environment – and we can do that with some changes to the tax system to ask the wealthiest in society to pay a little more”.
He said he expected Ms Reeves to say there was “no money” in the public purse due to the £22bn “black hole” Labour claims has been left by the last Conservative government.
But Mr Ramsay said he would tell the chancellor “she’s not looking in the right place”.
During the election campaign, the Green Party called for a wealth tax of 1% on assets worth over £10m and 2% on assets worth more than £1bn, claiming it would raise £15bn by the end of the parliament and impact fewer than 1% of UK households.
Speaking on Friday, Mr Ramsay stuck to the pledge, saying: “[These tax] changes are modest by the standards of many other European countries who recognise that having high quality public services and a greener economy needs investment.
“I proudly championed a wealth tax during the general election campaign, and I will do the same on budget day.
“And I will do the same every single day I hear this government claim that we can’t afford to pay for the necessary climate action, or to make sure everyone has a safe, affordable, warm home, or to fund our much loved NHS.”
The co-leader pledged to work with Labour “where we agree”, including on onshore wind projects or taking railways back into national ownership.
But he added: “In so many areas, ones that matter deeply to so many of us, Labour is getting it wrong.”
Speaking to Sky News after the speech, Mr Ramsay added: “The last government undoubtedly left the country in a mess. But Labour have more choices than they are saying.
“And they’ve chosen really cruel options, like cutting winter fuel payments to millions of pensioners… [keeping] the two-child benefit cap, which is putting 300,000 children unnecessarily into poverty.
“They’re cutting funding for nature friendly farming. It’s not good for farmers. It’s not good for the natural world.
“There are alternatives to these things that will enable us to invest in our public services and defend the environment.”
The Greens are holding their first party conference since their most successful general election to date, which saw them secure four seats in the House of Commons and two million votes.
It kicks off a season of political conferences, with all major parties due to meet in the coming weeks.