NEW YORK (CNNMoney.com) - Senate Majority Leader Bill Frist (R-Tenn.) said on Tuesday that the Senate would not be able to complete legislation addressing alternative minimum tax relief by the end of this year, the Associated Press reported.

That relief would extend for one year, through 2006, an increase in the levels of income that would be exempt from the AMT.

If the exemption levels are not increased, approximately 17 million taxpayers would be subject to the higher tax for the first time when they file their returns for tax year 2006.

But the increased exemption levels remain in effect for tax year 2005, so taxpayers filing their 2005 taxes in 2006 will not be burdened by the delay on the Hill.

It's unlikely, however, that lawmakers would not pass relief by early next year and make it retroactive Jan. 1 since the measure has broad bipartisan support.

"It's too politically volatile. People aren't going to want to vote against it whether it's taken up this year or next," said Helena Klump, an editor at Tax Analysts.

Frist's comments came at a time when the legislative calendars for both the House and Senate are crowded with bills, some of which -- like the tax and spending reconciliation bills -- will prove contentious.

The House and Senate have each approved AMT relief measures for 2006, but the Senate's measure was included in its overarching tax reconciliation bill, while the House's measure was included in a stand-alone bill. (To see why Democrats are concerned, click here.)

Frist had indicated that he might try to have the Senate take up the House's AMT bill this week, but a Senate aide told Tax Notes, a publication of Tax Analysts, that getting unanimous consent would likely fail.