The tax law gives preferential treatment to some kinds of income and allows special deductions and credits for some kinds of expenses. Taxpayers who benefit from these provisions of the law may have to pay an additional tax called the alternative minimum tax. It is a separate tax computation that, in effect, eliminates many deductions and credits and creates a tax liability for an individual who would otherwise pay little or no tax.
The exemption amount on Form 6251, line 5, has increased to $71,700 ($111,700 if married filing jointly or qualifying widow(er); $55,850 if married filing separately).
Also, the amount used to determine the phaseout of your exemption has increased to $510,300 ($1,020,600 if married filing jointly or qualifying widow(er)).
The exemption amount for certain individuals under age 24 is limited to the amount of their earned income plus $7,750. (See instructions)
For more information on this tax see the instructions for form 6251.