Sebastian Mallaby expresses some sensible thoughts on Sen. Max Baucus’s (D-MT) recent declaration of his desire to repeal the alternative minimum tax (AMT): [A] prescription so fiscally crazy that not even the Bush administration supports it. Indeed. Mallaby goes on to suggest a permanent AMT fix - in whatever form it may take - could be used as a chip to sweeten any future revenue-generation package, and Baucaus would be wasting this opportunity. But, more importantly, Mallaby also makes the case that a repeal of the AMT is highly undesirable for two very important reasons:

• It would be extremely expensive - "$750 billion-plus over a decade" and
• The AMT is a progressive tax which is particularly warranted because "in an era of rising inequality, you don't slay progressive monsters casually."

As we’ve argued before, the AMT does need a few adjustments to restore it to being an equitable part of a tax code riddled with so many loopholes and exceptions that sometimes millionaires pay little or no federal income tax at all, but full repeal is simply indefensible.