One of the problems with the AMT is that liabilities can vary greatly from year to year. In a recession year like 1990, when profits fall, capital-intensive firms like auto companies still have a lot of depreciation. That is what triggers a large AMT payment. Then in future years, when a company may not be covered by the AMT, it gets a credit for the AMT it paid in previous years. It also is notoriously complex, makes corporate planning more difficult and discourages capital investment.
More investment translates into higher productivity, higher wages and more jobs.
These problems with the AMT are now leading even many liberals to question the wisdom of this tax. For example, a new book from the Brookings Institution makes a strong case for repeal. Economist Martin Sullivan of Tax Analysts is even more critical. Moreover, it is all done for the sake of appearance. It exists so there will be no bad press about large corporations not paying any tax.