In unprecedented action, the IRS has jumped the gun and changed its Alternative Minimum Tax form – Form 6251 – to reflect the current estimate of what the AMT exemption amount would be if and when Congress enacts this year’s AMT patch.

Individual taxpayers should proceed with some caution at this point, however, until the law actually is changed. While it is expected that the current logjam between the Republicans and Democrats on these tax issues will break sometime soon, there always is the possibility that the final AMT patch numbers may not be exactly the same as those currently being estimated.

As discussed in a recent article, in response to pressure from the IRS to act on the patch in time for the IRS to finalize its forms and computer programs, the leaders of the Senate and House tax-writing committees sent a letter to the IRS Commissioner with their best estimate of what the patch amounts should be. In a somewhat surprising response to this letter, amounting virtually to a scolding, Commissioner Schulman wrote back to the Congressional leaders and informed them that he was directing his internal IT function to update the IRS’ computers for these changes, without waiting for them to act.

In the Commissioner’s letter, he reminded these Congressional leaders that if the legislation is not actually passed by the end of the year, the computers will have been programmed incorrectly, and substantial delays in processing these taxpayers’ returns will result if the IRS is forced to reprogram its computers once again. Certainly this is an accurate assessment of the situation, but it’s also surprisingly blunt in this not-so-subtle criticism of Congress for its delay in acting on this.

So what should AMT taxpayers do, here at year-end as they are trying to do their tax planning? While it is generally viewed as safe to assume that the patch will be enacted, whether it actually will be done before year-end or retroactively in 2011 is uncertain. The exemption amounts estimated by the Congressional leaders and now in the IRS’ computers and on the draft Form 6251 certainly are more accurate than assuming that no patch will pass, but there also is the possibility that the exact dollar amounts could change before this is finalized. Any such additional change, however, if there is one, should not result in a material difference in an individual’s final 2010 AMT liability.