Finance Secretary Derek Mackay faces a final Budget ultimatum from the Greens
He has already proposed making Scotland the highest-taxed part of the UK in plans published last month but Green co-convenor Patrick Harvie wants further hikes.
The Scottish Government’s hopes of getting its £38billion Budget through parliament hang in the balance because the SNP lacks a majority.
With the Tories and Labour set to oppose it, he is looking to the Liberal Democrats and Mr Harvie’s party for backing.
Mr Harvie has repeatedly called on Mr Mackay to raise taxes further after using new powers not to pass on a Tory giveaway for middle-class earners.
But with a Budget Bill expected to be published within days, the Left-wing environmentalist has ramped up demands for more raids on pay packets.
His six-strong bloc stood on a Holyrood election manifesto to introduce a 60p top rate of tax.
Mr Havie has also previously advocated introducing an extra tax band between 20p and 40p to boost local services.
Issuing his latest demand, Mr Harvie said the SNP’s draft Budget “showed no effort to work with others”.
We have outlined a range of options for them to make the tax system fairer
Green co-convenor Patrick Harvie
He added: “In discussions with ministers, we have outlined a range of options for them to make the tax system fairer, to reduce inequality in our society and to generate additional funds for public services.
“They have total freedom over rates and thresholds, and there is a clear need for them to use this flexibility.”
Mr Mackay has said he is “positive” about getting a deal, saying talks with the Lib Dems and Greens had shown “room for manoeuvre”.
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Patrick Harvie, of the Greens, wants further tax hikes
He has so far refused to change any income tax rates but will not follow the Chancellor’s plans to increase the threshold for paying the 40p rate of income tax from £43,000 to £45,000. Instead the threshold in Scotland will increase next April in line with inflation to £43,430.
It means everyone on the higher rate of income tax north the Border will pay £314 a year more in the next year than people elsewhere in the UK.
Scottish Conservative finance spokesman Murdo Fraser said: “The Greens want to hit hard-working families even harder.
“If Patrick Harvie gets his way, we would see punitive rates on higher earners that quite simply would drive talent out of Scotland, and mean that there would be less tax revenue to spend on public services, not more.
“Our economy is already lagging badly behind the rest of the UK, and businesses will be hoping that Derek Mackay resists this ultimatum to drag Scottish tax policy even further to the left.”
Last week Lib Dem leader Willie Rennie handed Mr Mackay a list containing £400 million worth of spending demands on education, mental health, police and transport.
But is willing to back the Budget without a 1p income tax rise, he has previously demanded.
Kezia Dugdale said it was ‘not good enough’ to pass on Tory cuts to the poorest
Labour has confirmed it will vote against it, because of £327 million of real terms cuts for councils. It will step up attacks with a Holyrood debate this week.
Leader Kezia Dugdale said: “It’s not good enough for the SNP to pass on Tory cuts to our poorest communities when there are powers to do something about it.”
A Scottish Government spokeswoman said: “We are in active discussions with other political parties about the Scottish Budget.
“We are considering the detail of the propositions that we have received to date and will continue to take forward constructive discussions on our budget plans.”