The upcoming tax season is expected to start on time for everyone except for certain taxpayers potentially affected by late enactment of the Alternative Minimum Tax “patch.” Following extensive work in recent weeks, the IRS expects to be able to begin processing returns for the vast majority of taxpayers in mid-January. However, as many as 13.5 million taxpayers using five forms related to the Alternative Minimum Tax (AMT) legislation will have to wait to file tax returns until the IRS completes the reprogramming of its systems for the new law.

IRS has targeted Feb. 11, as the potential starting date for taxpayers to begin submitting the five-related returns affected by the legislation. The February date allows the IRS enough time to update and test its systems to accommodate the changes without major disruptions to other operations related to the tax season.

Source: IRS.gov
http://www.irs.gov/newsroom/article/0,,id=176605,00.html