Six out of ten Scots say they would be prepared to pay more in tax if the cash raised went on improving public services or tackling inequality.
Research by polling company Survation found 60% said they would "personally be willing to pay more tax" - with only 15% opposed.
The research, carried out for campaigning organisation 38 Degrees, was released a week before Finance Secretary Derek Mackay will reveal his Budget plans for next year to the Scottish Parliament.
A Scottish Government spokesman confirmed this was now in the "final stages of preparation", with the draft Budget plans being discussed by Nicola Sturgeon's cabinet.
There is widespread speculation Mr Mackay is to raise taxes for better-off Scots, using powers Holyrood has over income tax rates and bands.
Survation's research showed 61% are in favour of proposals which could raise £200 million by raising taxes on higher earners at the same cutting the amount paid by lower-paid Scots.
A total of 14,000 people have also signed a petition from 38 Degrees calling for such a change.
Gordon Maloney, a campaigner with 38 Degrees in Scotland, said: " These results show the public have come down on the side of bold tax reform to help fund Scotland's public services.
"With the vast majority backing tax rises for better treatment in our hospitals, education for our children and a more equal society - and almost two in three Scots willing to personally pay more - the government has a mandate to be bold.
"MSPs can either be ambitious on tax reform and receive the public's backing - or they can kowtow to the interests of the very richest."
Stephen Forster, a 38 Degrees member from Glasgow who would be happy to pay a little extra in tax, said: " We cannot complain about lack of services and then not help generate funds for those services simply because we want to be greedy.
"If I can spare a little more money than a person earning less than me, then I should do so."
:: Survation questioned 1,017 people aged 16 and over in Scotland between November 27 and 30.
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