This year too, Senate Republicans have strongly opposed the extension of existing tax breaks if accompanied by increased tax revenues elsewhere, and Senate Finance Committee Chairman Max Baucus, D-Mont., has indicated that it may be inevitable to accept an unpaid-for AMT fix.

The offsets in the package before the House Wednesday include a measure that would raise $31 billion over 10 years by increasing the tax rate on the share of investment profits received by private equity and hedge fund managers, also known as carried interest. Managers of private equity and hedge funds are now generally taxed at the 15 percent capital gains rates on the profits they share instead of the 35 percent individual income tax rate that would normally apply to high-income individuals. The bill would tax most of their profit-sharing income at the higher 35 percent rate.

The bill would also disallow certain deductions oil and natural gas companies receive for domestic production, bringing in $13.6 billion.

A third provision requires credit card companies to inform the IRS of payments they make to merchants for credit and debit card transactions. This would allow the IRS to better track business income, raising some $9.8 billion. Finally,the bill closes a loophole used by foreign multinationals to avoid taxes on income earned in the United States, raising almost $7 billion.

The White House threatened a presidential veto of the AMT fix if it is accompanied by the new revenue provisions. "The administration urges Congress to reduce the risk of disruption to the 2009 tax filing season by eliminating tax increases from the bill," it said in a statement.

The fight over offsets last year forced the IRS to delay sending out refunds to millions of taxpayers because it had to adjust its computer programs to comply with the late changes in the AMT law.