This excerpt taken from the ROST DEF 14A filed Apr 14, 2008.
Incentive Stock Options. A participant recognizes no taxable income for regular income tax purposes as a result of the grant or exercise of an incentive stock option qualifying under Section 422 of the Code. Participants who neither dispose of their shares within two years following the date the option was granted nor within one year following the exercise of the option will normally recognize a capital gain or loss upon the sale of the shares equal to the difference, if any, between the sale price and the purchase price of the shares. If a participant satisfies such holding periods upon a sale of the shares, we will not be entitled to any deduction for federal income tax purposes. If a participant disposes of shares within two years after the date of grant or within one year after the date of exercise (a disqualifying disposition), the difference between the fair market value of the shares on the option exercise date and the exercise price (not to exceed the gain realized on the sale if the disposition is a transaction with respect to which a loss, if sustained, would be recognized) will be taxed as ordinary income at the time of disposition. Any gain in excess of that amount will be a capital gain. If a loss is recognized, there will be no ordinary income, and such loss will be a capital loss. Any ordinary income recognized by the participant upon the disqualifying disposition of the shares generally should be deductible by us for federal income tax purposes, except to the extent such deduction is limited by applicable provisions of the Code.
In general, the difference between the option exercise price and the fair market value of the shares on the date of exercise of an incentive stock option is treated as an adjustment in computing the participants alternative minimum taxable income and may be subject to an alternative minimum tax which is paid if such tax exceeds the regular tax for the year. Special rules may apply with respect to certain subsequent sales of the shares in a disqualifying disposition, certain basis adjustments for purposes of computing the alternative minimum taxable income on a subsequent sale of the shares and certain tax credits which may arise with respect to participants subject to the alternative minimum tax.