Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

How converted stock is taxed due to an acquisition
I don't think its a taxable event since no income has been constructively received (talking about the RSU shareholders here). I believe you're right with the IRC 1033, and the basis of the RSU is the basis of the original stock option (probably zero). Edit: see below. However, once the stock becomes vested - then it is a taxable event (not when the cash is received, but when the chance of forfeiture diminishes, even if the employee doesn't sell the stock), and is an ordinary income, not capital. That is my understanding of the situation, do not consider it as a tax advice in any way. I gave it a bit more though and I don't think IRC 1033 is relevant. You're not doing any exchange or conversion here, because you didn't have anything to convert to begin with, and don't have anything after the "conversion". Your ISO's are forfeited and no longer available, basically - you treat them as you've never had them. What happened is that you've received RSU's, and you treat them as a regular RSU grant, based on its vesting schedule. The tax consequences are exactly as I described in my original response: you recognize ordinary income on the vested stocks, as they vest. Your basis is zero (i.e.: the whole FMV of the stock at the time of vesting is your ordinary income). It should also be reflected in your W2 accordingly.