Humza Yousaf has been urged to be bold on taxation by a group including anti-poverty campaigners ahead of a key statement to Parliament.
The First Minister will lay out his priorities on Tuesday in an address to Holyrood which is expected to set the tone for his premiership.
In his bid for the leadership, Mr Yousaf said he would consider the creation of another tax bracket for those earning more than £43,662.
The IPPR think tank, which is among those calling on Mr Yousaf to announce tax reforms on Tuesday, has said the change could raise as much as £257 million and would be enough to increase the Scottish Child Payment to £40 per week.
“There is no shortage of money in Scotland. The First Minister now must prove that there is also no shortage of the political courage needed to take the urgent action required to build a fairer, more sustainable future.
“Failure to do so would short-change us all – Scotland simply can’t afford to be timid on tax any longer.”
Ruth Boyle, the policy and campaigns manager at the Poverty Alliance, said the tax system in Scotland “simply hasn’t kept pace with Scotland’s growing inequality of wealth and income”.
“It’s time for the Scottish Government to use our tax powers in a progressive way, to raise the investment we need for the just and compassionate society that people believe in,” she added.
Child Poverty Action Group (CPAG) director John Dickie added: “With families across the country struggling to put food on the table and pay the bills and one in four of our children still living in poverty, this is absolutely the time for the new First Minister to be bold in his use of Scotland’s tax and benefit powers.
“Harnessing Scotland’s undoubted income and wealth and investing in tackling poverty through, for example, the Scottish Child Payment, are vital to ensuring every family has the resources they need to give their children a decent start in life.”
A Scottish Government spokesman said the First Minister had “already indicated his commitment to progressive taxation” ahead of his statement to MSPs on Tuesday.
“Changes to income tax in Scotland came into force earlier this month and are estimated to raise more than half a billion pounds of additional revenue this financial year to support vital public services,” the spokesman said.
“In addition, the Scottish Government has launched a consultation on giving new powers to local authorities, which would allow them to increase council tax on second homes and empty homes.”