'Fiscal cliff' could put millions into 'AMT shock'

(CNBC) One of the key questions lurking in the “fiscal cliff” talks — though well below the public’s radar — is what happens to the alternative minimum tax, or AMT.

Implemented in 1969 to make sure upper-income Americans pay their share of taxes, the AMT has increasingly snared more middle-income Americans over the years because it was never indexed for inflation.

During the 2011 tax year for example, the AMT hit single taxpayers with incomes as low as $48,450 and joint filers making only $74,450.