Per the Instructions for Form 6251 Alternative Minimum Tax – Individuals, on page 9:

Part II—Alternative Minimum Tax

Line 5—Exemption Amount

If line 4 is more than the amount shown for your filing status in the middle column of the chart on line 5, see the Exemption Worksheet to figure the amount to enter on line 5.

Form 1040-NR. If you are filing Form 1040-NR, use the following chart to figure the amount to enter on line 5. However, if line 4 is more than the amount shown for your filing status in the middle column of the chart, use the Exemption Worksheet to figure the amount to enter on line 5.

Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.