Incentive stock options (ISOs) 101
ISOs are the most tax-favoured form of equity compensation available to employees, and the easiest to mishandle.
The lifecycle
Grant, vest, exercise, hold, sell. Tax consequences attach to exercise (AMT) and sale (capital gains or ordinary income), never to vesting.
Qualifying disposition
Hold shares more than two years from the grant date and more than one year from exercise, and the entire gain is long-term capital gain. Break either clock and you have a disqualifying disposition taxed largely as ordinary income.
Deadlines that bite
ISOs must be exercised within 90 days of leaving most employers or they convert to NSOs. Grants also expire, usually ten years from grant.
This article is educational and not tax, legal, or financial advice. Talk to a CPA or tax advisor about your specific situation.