Form 6251 is used to calculate the Alternative Minimum Tax (AMT) for individuals. It requires the taxpayer to enter various amounts from their Form 1040 or Form 1040NR, as well as other adjustments and deductions. The form also includes a tax computation using maximum capital gains rates. The form is to be attached to Form 1040 or Form 1040NR. For more information and instructions, visit www.irs.gov/Form6251.