AUGUSTA, Maine — Mainers would see their federal income tax burden reduced by an estimated $663 million this year if the tax provisions in the Senate stimulus bill make it into the final package. But the state’s finance commissioner cautioned lawmakers that the bill is a moving target.

“I got a printout at around noontime of the Senate version with all the programs on it, and literally before I could figure out how to put it on a single piece of paper, the Senate changed the bill and added $25 billion more in infrastructure projects,” he said. “It was outdated while the page was still warm.”

Mainers will pay about $287 million less in personal income taxes if the Senate proposal becomes law according to the preliminary analysis of the impact of the proposed changes to the Alternative Minimum Tax by Maine Revenue Services.

The tax has been a major issue in Congress for the last few sessions. The tax was created in 1969 to ensure all taxpayers, no matter how many deductions they had, would pay some federal income tax. But unlike the income tax brackets that are adjusted every year for inflation, the AMT is not and more and more taxpayers were finding the tax applied to them.

For example, for tax year 2008, about 85,000 Maine taxpayers — many owners of small companies that pass through their business income to their personal income tax — would have been affected by the AMT. Congress passed a one-year fix for tax year 2008 last September.

“I strongly supported the AMT relief the Finance Committee added to the stimulus legislation last week,” U.S. Sen. Olympia Snowe, R-Maine, said. “AMT was one of several tax initiatives I worked to secure in the stimulus bill that will help Maine and the rest of the nation cope with the devastating economic conditions.”

She serves on the tax writing Finance Committee that developed the tax cuts portion of the Senate stimulus bill. It has several other provisions that would reduce the taxes of various groups of Mainers. For example, unemployment insurance benefits would not be subject to federal income taxes. That is an estimated $6.7 million benefit to workers that have lost their jobs.

Snowe said the AMT provisions and the waiving of income taxes on unemployment help maximize the tax credit provisions that will directly lower the taxes of individuals up to $500 and couples up to $1,000.

Low said that Maine Revenue Services has done a “rough estimate” on the impact of the tax credit on Maine and believes it will be about $326 million. The Senate measure also expands the earned income tax credit that would help low-income Mainers and would expand the refundable child care credit.

The measure also includes several business tax breaks designed to encourage investments and the hiring of new workers. For example, the Senate measure continues a provision that allows businesses to write off the first $250,000 of investments in a tax year. Maine has limited that to $25,000 on state income taxes, a sore point with the business community.

“There are some conformity issues, but I don’t think that many,” Low said.

Given the state’s revenue problems, Gov. John Baldacci has said he doubts Maine can conform to federal tax cuts that will cost the state revenue.

The timing of job creation is of great concern to the Maine Legislature’s Appropriations Committee. They start a month of hearings next week on the state two-year budget that starts July 1, 2009, based on income estimates that may be changed by the impact of the total stimulus package.

“And even after the Senate gets done with their bill, there will be a conference with the House, and the numbers can change again,” Low said.

Members of the Appropriations Committee told Low they want updates as the stimulus package works its way through Congress.