In an interview with the BBC’s Sunday with Laura Kuenssberg programme, Polanski suggested a wealth tax could raise between £15bn and £25bn a year.
Challenged that other countries which have implemented similar proposals have found they raised much smaller sums, he said: “Whatever you’re going to create from a wealth tax, it’s ultimately about reducing inequality.
“This isn’t about creating public investment, we can do that anyway, we don’t need to tax the wealthy to do that. This is ultimately about tackling the deep inequality in our society.”
However, he admitted the idea was not even “close to a panacea” and said capital gains tax – which is charged on profits made from the sale of an asset such as a second home or shares – also needed to brought in line with income tax.
“We need to tax unearned wealth as much as we tax earned income,” he added.
Pressed over whether lower and middle-income earners would also have to contribute more for better public services, Polanski insisted the focus at the moment should be on the wealthiest.
But he added: “Once we start to move to a better footing as a society, where we have better public infrastructure and services, then I think it is legitimate to say paying tax is something that’s actually patriotic, we should be proud of contributing to this country, to making sure we have an NHS that works, that we have public transport that works.
“And, yes, everyone will have to pay for that, but ultimately this is about where is the biggest burden, and that should be on the people with the broadest shoulders.”