Not only turbotax, but sometimes your brokerage firm (in case Fidelity) screws up calculating exercising options. I would've owed $20,000 more in taxes because

Not only turbotax, but sometimes your brokerage firm (in case Fidelity) screws up calculating exercising options. I would've owed $20,000 more in taxes because the software failed to account for the amount that was already withheld.