13 May 2014
The AMT is a parallel tax system that operates in the shadow of the regular tax, expanding the amount of income that is taxed by adding items that are tax-free and disallowing many deductions under the regular tax system .
To figure out whether you owe any additional tax under the Alternative Minimum Tax system, you need to fill out Form 6251. If the tax calculated on Form 6251 is higher than that calculated on your regular tax return, you have to pay the difference as AMT in addition to the regularly calculated income tax. It can result in you paying hundreds or even thousands of dollars in additional taxes.