With employee stock options there are two taxable transactions. First, when the shares vest--that's ordinary income reported on your W-2. Second, when you sell the shares, which often occurs on the same day. The sale is reported on Form 1099-B. The key to avoiding double taxation is to add the ordinary income shown on your W-2 for the shares vesting to your basis for the subsequent sale. In most cases this results in little or no gain or even a small loss due to sales commission.
Please follow this link for more information. https://turbotax.intuit.com/tax-tools/tax-tips/Investments-and-Taxes/Incentive-Stock-Options/INF1204...
