[patio11]

Confirm this with your tax advisor, but FMV at exercise is your basis in later years (generally because the difference in FMV and strike will have caused you a taxable event).

c.f. https://www.untracht.com/news-insights/vantagepoint-newslett...

Edit: Consider the case where this were not treated as true. You're clearly not going to pay $2 strike, exercise at $5 ($3 of employment income due to the bargain element), sell at $10 in a later year and pay on $8 of capital gains, right?

[andrewem]

I'll note for conceptual understanding (by people who aren't patio11, who I'm sure understands this all far better than me) the general point that a gain or loss on the sale of a capital asset is how much money you got from selling it minus how much you "paid". More technically, how much you "paid" is called the basis, and you can do things that adjust the basis as patio11 noted above.

For general information on this topic see https://www.irs.gov/newsroom/capital-gains-and-losses-10-hel...