The alternative minimum tax (or AMT) is an extra tax some people have to pay on top of the regular income tax. The original idea behind this tax was to prevent people with very high incomes from using special tax benefits to pay little or no tax. Over time the AMT has increased its reach and now applies to the middle class as well as the rich. Proposals to repeal or reform the AMT have not made it through Congress although many want to get rid of this tax. If you don't itemize deductions on your tax return you don't have to worry about it.