The Deputy First Minister and finance secretary refused to agree with a demand by Scottish Tory leader Ruth Davidson not to raise taxes when powers begin in 2016.
Under the 2012 Scotland Act, the Scottish Government will be able to decide on the first 10p of income tax raised on all the rates in Scotland.
However, under the Smith Commission proposals which are in the current Scotland Bill, Holyrood will have complete control over income taxes on wages in Scotland and will be able to vary the basic, higher and top rates differently to the rest of the UK.
Asked about the Tory pledge not to raise income tax, Mr Swinney said in an interview: “I can’t give that pledge today and I won’t give it.
“Because I want to make sure that my party has the opportunity to exercise the choice that we believe to be appropriate in the relevant circumstances, the 2016 election and beyond, to ensure that we take the right decisions.”
Asked whether he would have any intention of increasing or reducing both rates of income tax, Mr Swinney said: “We’ll obviously give consideration to that as we formulate our proposals for the 2016 election and for subsequent budgets beyond that if we’re fortunate enough to be the government of Scotland.”
The Scottish Tories warned that Mr Swinney’s comments mean the SNP could hit Scottish taxpayers harder after the powers are devolved.
John Lamont, Scottish Conservative chief whip, said: “John Swinney failed to offer any assurances to hard-pressed taxpayers on how new income tax powers will be used by the SNP when they start being introduced next year.
“Our view is that Scottish families and businesses deserve a simple commitment that Scottish taxes will not be used to raise more than the current UK system.”