Alternative minimum tax (AMT) is a tax that was originally designed so that high-income taxpayers who avoided paying regular income tax by using various tax preference items would at least pay some income tax.
Now, with tax rate reductions, a high amount of itemized deductions, or a high number of dependents, it is possible that AMT will apply to a return. The AMT is the difference between the regular tax rate and the calculated alternative minimum tax. The AMT is calculated on Form 6251, reported on Line 45 of IRS Form 1040, and added to your regular tax.
Alternative minimum tax is reported on the Summary screen and in the Alerts section of the program. From within your TaxACT return (Online or Desktop):