[TimTheTinker]

Note, this only applies to "early exercise" under 83(b), which is exercising an option grant prior to the grant vesting. More info: https://carta.com/blog/early-exercise-stock-options/

Not all startups allow this type of early exercise. If you exercised ISOs/NSOs only after they vested, this problem can't apply to you.

[PopAlongKid]

Excellent point. Many don't understand that 83(b) only applies to property that has been transferred but not vested. Sometime people mistake a lock-up period on selling stock as equivalent to not being vested -- it is not.