Sinn Féin has called for the abolition of the universal social charge and the introduction of a third rate of tax on incomes over €100,000.
The party's justice spokesman Aengus Ó Snodaigh said a rate of 48 per cent would apply to individuals earning over that sum.
He said the proposal had been costed by the Department of Finance at €410 million, which was "virtually the same" as the €420 million the social charge would raise this year.
He said this demonstrated that the outgoing Government had done no impact assessment on the introduction of the universal social charge and the effect it would have on communities.
"But also, it didn’t look around to see if there was an alternative, despite the fact that we made this submission to them well in advance of the budget."
Mr Ó Snodaigh said he did not have an exact figure for the number of people earning over €100,000.
But he said every one of the proposals in Sinn Féin’s pre-budget submission had been costed by the Department of Finance, either through direct contact from the party or through information provided in response to parliamentary questions.
When it was put to him that this would mean Sinn Fein would be the “high tax” party if in government, Mr Ó Snodaigh said: “If you are wealthy you will pay your proper amount of tax. If you are poor, you shouldn’t be paying at the same rate as those who have money.”
He said the charge was "regressive" and that those on lower incomes were being penalised by the Government for mistakes it and bankers had made.
"It’s pure and simple: those who have the most should have to pay the most," he said.
"I don’t believe that those who are the lowest paid in our society should take the burden of taxation and I don’t believe anybody on the minimum wage should be taxed."
Mr Ó Snodaigh said many people who had received their wages in the past week had realised they now had less disposable income, which would affect local economies.
"That means that you’re going to have more closures of small retail shops and small businesses around the country, which is the exact opposite of what we need to see happening in the economy as we are in an economic crisis."
Mr Ó Snodaigh said he hoped Sinn Féin would have a “good election” and said polls indicated it would do better than it had in the 2007 general election.
The polls were also indicating that Labour and independents would do well. He said that, at that stage, it would be possible to look at the make-up of the next government.
"I would prefer if there was a new government in this island, which was left-leaning and had the progressive policies that we put forward."
Mr Ó Snodaigh said he would not countenance any coalition with parties of the right who were not endorsing the policies of Sinn Féin.
Asked if he could see his party entering into government with any Green Party TDs returned, he said he did not believe there would be any elected.
But he was “not ruling anyone in or out”, other than right-wing parties who had a "different attitude" towards getting out of the current crisis.
Mr Ó Snodaigh said he hoped all the party leaders, including Sinn Féin president Gerry Adams, would be represented in TV debates in advance of the election.