I need advise. In 2017 my wife and I exercised Intensive Stock Options (ISO) from her company. ISO exercised amount minus what we owed her company was included in her W2, we paid 1040ES to cover Taxes. Yet last year IRS send me CP2000 note where they state that,exactly same date exercised ISO, were presented as sold security and requested Tax and penalties on it. I responded explaining that the amount is included in W2 and we paid Taxes correspondingly with proof of W2 included. Yet this year they send same note requesting much higher penalties for the same ISO shares we already had been Taxed for. Once again I mailed them proof that all exercised shares were included in W2 but not sure what else I can do.