A December 10 Wall Street Journal rant against PAYGO asserts that the AMT is careening out of control because "Democrats who designed it failed to index it for inflation and raised AMT rates under Bill Clinton in 1993." To be sure, indexing the AMT exemption would have kept millions of taxpayers out of its clutches but blame for that oversight lies with many Congresses and administrations. Never in the tax's 40-year existence has either Congress or the president seriously tried to permanently index the AMT. And the decision in 2001 to cut regular income taxes without also reducing the AMT has played a huge role in AMT's growth.

The Omnibus Budget Reconciliation Act of 1993 (OBRA93) increased both the regular income tax and the AMT. That law created two new top regular tax brackets, raised the AMT rate from 24 percent to 26 and 28 percent, and increased the AMT exemption by 12.5 percent.

Was OBRA93 to blame for the AMT hitting more taxpayers? Greg Leiserson and Jeff Rohaly posed that question earlier this year and reached a "not guilty" verdict. They estimated that going back to pre-1993 AMT law without increasing the AMT exemption would result in 26.6 million taxpayers falling under the AMT in 2007, compared with 23.4 million under current law. The OBRA93 combination of higher rates and higher exemptions would have kept more than 3 million taxpayers off the AMT rolls.

Failure to index the tax rightly deserves much of the blame for the AMT's encroachment but this argument comes years too late. The obvious time to index the AMT would have been a quarter century ago when Congress indexed the regular income tax in 1981or five years later in the 1986 Tax Reform Act. Both of those non-events occurred during the Reagan Administration.

What we need to remember is that the AMT has been the product of bipartisan neglect, not one party's. Recognizing that fact—rather than pointing fingers—might even lead to a bipartisan solution.