If you exercised and sold 25% of the stock, did you hold the other 75%? Did you receive Form 3921 or 3922? 3922 is for ESPP, which you also may have received, but they are different than ISOs. If you have additional shares that you did not sell, you will need to report those in the Federal > Wages & Income > Investment Income > ISO Exercise and Hold section. They may have a taxable impact on your return, they may not, depending on the amount and other items on your tax return.
If you exercised and sold 25% of your stock right away, that should have been included on your W-2. If you did not receive cash, but instead it was withheld for taxes, then those taxes should also be on your W-2. The W-2 should have both the proceeds from the sale in Box 1 and your regular wages. The sum makes up your compensation for the year from your employer.
When entering the 1099-B for the sale, the cost basis should be adjusted using the information from Form 3921. I would check the entries and ensure that everything is in there correctly. If the sale was already included as part of your compensation on your W-2, which it should have been, then the impact on your taxes should be minimal.
@macd05
