The SNP have vowed to back the re-introduction of the 50p tax rate for people across the UK who earn more than £150,000 a year.
The move, aimed at redistributing wealth to pay for public services, matches Labour policy and was announced at the SNP conference in Glasgow yesterday.
Stewart Hosie, deputy leader of the SNP, told delegates that Labour has previously blocked plans to stop the tax cut for millionaires.
“We still think that those with the very broadest shoulders should bear a slightly larger share of the burden,” he added.
“In the next parliament, SNP MPs will support the re-introduction of the 50p tax rate for the very wealthiest in our society.”
Labour finance spokeswoman Jackie Baillie claimed there was “confusion at the heart of the SNP” because Alex Salmond asserted last week there would be no new taxes.
“Notably there was no mention of the £7.6billion of cuts that would be inflicted on Scotland by the SNP were they to follow through with full fiscal autonomy,” she added.
“Only Labour has a real plan to tackle austerity and deliver real social justice.”
Scottish Conservative enterprise spokesman Murdo Fraser branded the tax policy an “anti-business move which would harm job and wealth creation in Scotland”.
Mr Hosie set out the SNP’s priorities on the basis it holds the balance of power at Westminster after the election in May.
They include abolishing the so-called bedroom tax, scrapping zero-hours contracts, boosting the national minimum wage to £8.70 by the end of 2020, resisting the renewal of Trident and a tax-dodgers Bill.
Mr Hosie told delegates that the party was focused on winning the general election in Scotland to ensure the Westminster parties kept their promise of new powers for Holyrood.
“A vote for the SNP will, possibly for the first time, give the Scottish people the power to achieve real change at Westminster,” he added.
“And we need to change – not just to say no to austerity but to deliver real economic decision making to Scotland.”
Former First Minister Alex Salmond took part in a question and answer session and promoted his new book about the last 100 days of the referendum campaign.
“In retrospect my only regret about the currency is I should have done earlier what I did in the second television debate, when I laid out the four options that people in Scotland would have,” he said.
But Mr Salmond, MSP for Aberdeenshire East, insisted that while the SNP had lost the referendum, “we are substantially on our way to winning Scotland.”
First minister Nicola Sturgeon said the SNP was preparing “to lead the UK” with her predecessor expected to be a big voice at Westminster.
And Deputy First Minister John Swinney vowed that the party would “fight tooth and nail” to protect vulnerable Scots from the “swingeing welfare cuts”.
Delegates backed a move to allow all-female shortlists in the Holyrood election next year in the event of a constituency MSP standing down.