Question 1

What's the main tax difference between ISO and NSO?

Accepted Answer

NSO: bargain element taxed as ordinary income at exercise (37% federal + FICA + state). ISO with qualifying disposition: NO regular tax at exercise, only LTCG (20% + 3.8% NIIT) on entire spread at sale. ISO can also trigger AMT \u2014 but creates a recoverable Minimum Tax Credit.

Question 2

What's the ISO qualifying disposition holding period?

Accepted Answer

More than 2 years from grant date AND more than 1 year from exercise date \u2014 BOTH conditions must be met. If you sell earlier (disqualifying disposition), the spread becomes ordinary income just like an NSO \u2014 losing the tax advantage. Track both dates carefully.

Question 3

Does ISO exercise trigger AMT in 2027?

Accepted Answer

Yes \u2014 the bargain element at exercise is an Alternative Minimum Tax preference item. For high earners with large ISO exercises, this can trigger substantial AMT. The good news: AMT from ISO timing creates a Minimum Tax Credit (Form 8801) that's recoverable in future years when regular tax exceeds tentative AMT.

Question 4

What's the $100K ISO annual limit?

Accepted Answer

Per IRC \u00a7422(d), only $100,000 worth of ISOs (measured at grant-date FMV) can become exercisable in any single calendar year. Excess is treated as NSO. If your grant vests $200K in a single year, only $100K gets ISO treatment \u2014 the rest is NSO. Companies stagger vesting to maximize the limit.

Question 5

Should I early-exercise my ISOs?

Accepted Answer

If you (a) can afford the strike price + AMT, (b) believe in the company's success, (c) can hold 5+ years to a 2x+ exit, then YES \u2014 early exercise + 83(b) is the most tax-efficient strategy. You convert all future appreciation to long-term capital gain at 20% + 3.8% instead of ordinary income at 37% + NIIT. Risk: lose strike if company fails.

Question 6

What happens with ISO if I leave the company?

Accepted Answer

You typically have 90 days post-employment to exercise vested ISOs \u2014 any later loses ISO status (treated as NSO). Some plans extend this to 7-10 years post-employment but the IRS still requires the 90-day window for ISO treatment. Many startup employees leave significant ISO value on the table by not exercising in time.

ISO vs NSO Stock Option Tax 2027 Comparison Calculator

ISO vs NSO Tax Mechanics

ISO Qualifying Disposition: The Holy Grail

ISO AMT Trap

Strategy: Early Exercise + 83(b) + ISO