Corporate AMT burden borne by small number of large corporations.

According to a recent Government Accounting Office report, of the 2.1 million corporations potentially subject to the corporate alternative minimum tax (AMT), only about 30,000 paid any AMT. Further, 85% of the total AMT burden was borne by about 2,000 large corporations.

The report resulted from a study of the years 1987 through 1992. It should be noted that few of the 2,000 corporations had to pay AMT every year.

Most of the corporations with AMT liability - generally in the manufacturing, transportation and finance industries - experienced tax rate increases of a few percentage points. Corporations in the mining industry, however, suffered a 4-to 6-point tax rate increase because of AMT liability. These increases included the effect of AMT credits.

Despite the low number of corporations with an AMT liability, about 400,000 corporations have to file an AMT form or keep related records.