Madison -- A tax increase on the working poor won’t trigger a supermajority vote in the Legislature on the state budget, GOP lawmakers said Wednesday.

But nonpartisan legislative attorneys found it more difficult to say whether a two-thirds vote of lawmakers would be required. That's significant because to reach the two-thirds threshhold Republicans would need to accomplish the unlikely task of winning over significant numbers of Democratic votes.

On Tuesday, the Joint Finance Committee voted to cut the Earned Income Tax Credit by $56.2 million over two years as part of the 2011-’13 state budget bill. That move has been scored as an income tax increase by the Legislature’s non-partisan budget office since it will either lower refunds or raise taxes for some low-income state residents.

That has Democrats asking about a law that was passed by GOP lawmakers and Gov. Scott Walker in February requiring a two-thirds vote of lawmakers to approve any increase in state sales or income tax rates.

Rep. Robin Vos (R-Rochester), the co-chairman of the Joint Finance Committee, said that the cuts to the tax credit program wouldn’t require the budget to be approved by a two-thirds margin.

That’s because the tax credit program doesn’t raise state income tax rates and because most of the tax credits go to state residents without any income tax liability as a way to make low-wage work more attractive.

“When I voted for the bill it was about rates and people who owe money based on the work that they performed,” Vos said.

A report by the Legislative Fiscal Bureau says that a majority of non-partisan legislative attorneys consulted on the proposal agree that a two-thirds vote won’t be needed.

But, “others suggested that an argument could be made that the proposed changes could trigger the requirement because the change is economically equivalent to (a tax increase),” the report says. “It is not possible to determine how the courts will interpret the provision.”

Todd Berry, president of the Wisconsin Taxpayers Alliance, said that the Earned Income Tax Credit is "admittedly a strange duck."

"If I had to pick one or the other I'd call it a tax increase," Berry said.

But Berry said he didn't think a change in the credit would trigger the two-thirds requirement because it didn't affect the state's overall income tax rates.