Those options have no value until you actually purchase and sell them. They can not currently be valued, so you have no idea how much you have been paid, if anything. Also, you should find out if they are considered as stock or salary. Capital gains are taxed at a different rate from earned income. Who knows the value of the stocks prior to any (hypothetical) gain?
I’m just guessing, but if were the IRS (and thank goodness I’m not), I would charge income tax on the amount up to the IPO price, and then capital gains tax on any gains you have made when you sell the stocks.
If you have to pay for the stock options at the IPO price, then you don’t pay the income tax, since there is no income, and all you have is the capital gains tax.
But I’m not an accountant, nor am I the IRS, so you should check with an accountant first.